1. Sex is 
beneficial for both the heart and the blood circulation, especially in 
the brain. While having sex, the heart rate goes from 70 beats per 
minute to 150, a good training for the heart. Having sex thrice a week 
decreases the risk of heart attack by 50 %. Also during the sex 
intercourses, the breath is deeper, meaning a better oxygenation. 
2.
 The mental and emotional health balance is clearly tuned by sex. People
 who are involuntarily celibate or abstinent and often exhibit 
depressive feelings (like anger, frustration, self-doubt, paranoia and 
even depression) are driven into this by "missed opportunities", due to 
living without having sex. 
In fact, in case of light 
depressions, after having sex the brain releases endorphins, that 
decrease stress, inducing a state of euphoria.
It seems also to 
be something in the sperm contributing to the good effect on the mood. 
Researches showed that women whose partners used condoms were more prone
 to depression than others. This is supposed to be linked to 
prostaglandin, a chemical found in the sperm and absorbed in the vaginal
 tract, modulating the woman's mood. Semen appears to act as an 
antidepressant in women. 
Women who have sex without condoms are 
also more likely to be victims of the rebound effect following the 
breakup of their relationship, pointing that there is a withdrawal 
effect that influences depressiveness when semen exposure stops. 
Anyway,
 protected or not, sex and orgasm do cause a release of endorphins, the 
"happiness" brain hormone that 'brings' the good mood. 
Even more important is the fact that sex strengthens the bound of the couple, self esteem, positive thinking and optimism. 
A
 2007 British research proved that sex is better than money in making 
you happy, and being sexually active indeed brings a happy life. But 
more financial power doesn't bring you more sex. 
Sex "enters so strongly (and) positively in happiness equations" that a higher frequency of sexual contacts from once monthly to once weekly is 
similar to the happiness level increase brought by an additional $50,000
 in income for the average American. The happiest individuals were those
 getting the most and regular sex: married people, or those involved in a
 relationship, who declared 30% more sexual activity than bachelors. A 
stable marriage was figured out to bring the same happiness levels 
provoked by an extra $100,000 earning annually, while divorce was 
equivalent to a happiness decrease of $66,000 each year. 
Psychologists
 already knew that happy people are usually more sexually active, and 
many studies confirmed that people who are depressed have less sex. It 
is sure that mind and sex fuel each other. 
3. Sex eliminates 
stress. You know the feeling of total relaxation and calm following a 
sexual intercourse. A subsequent profound calming sleep follows, with 
great effect in combating the stress, and persons with a regular sex 
life sleep better and feel better the next day. 
4. Sex means 
softer skin. While having sex, a woman's body doubles the estrogen 
level, and this makes her hair shine while the skin becomes softer. 
5.
 Long term researches showed that regular basis sex increases the 
humans' lifespan. For the same age and health, those who had orgasms 
more frequently had half the death rate of men who did not have such 
frequent orgasms. This could be due to the plummeting stress hormones, 
reaction that installs after we have sex. Frequent orgasms (about 100 
per year) have been linked to an increase of 3-8 years in a person's 
lifespan and a decrease of death risk of 50%. 
6. Sweating while having sex cleanse the skin pores, making the skin brighter and decreasing the risk of developing dermatitis. 
7.
 Sex can keep you fit, burning extra-pounds. Quickies of 20 minutes 
weekly mean 7 500 calories annually, that's as much as you consume on 
120 km (745 mi) of  jogging. A sex session can burn about 200 calories. 
This is like running 15 minutes on a treadmill! 
If this helps, 
here is a guide on your sex metabolism 
(http://members.aol.com/evilsuzie/ia/sexcalories.htm) (however, the 
following statements have not been scientifically proven...yet): 
OPENING HER BRA:
With both hands........................ 8 Calories
With one hand.......................... 22 Calories
With your teeth........................ 85 Calories
PUTTING ON A CONDOM:
With an erection....................... 6 Calories
Without an erection.................... 315 Calories
PRELIMINARIES:
Trying to find the clitoris............ 8 Calories
Trying to find the G-Spot.............. 192 Calories
POSITIONS:
Missionary............................. 112 Calories
69 lying down.......................... 178 Calories
69 standing up......................... 312 Calories
Wheelbarrow............................ 386 Calories
Doggy Style............................ 400 Calories
Italian chandelier..................... 972 Calories
ORGASMING:
Real................................... 112 Calories
Fake.................................. 315 Calories
POST ORGASM:
Lying in bed hugging................... 18 Calories
Getting up immediately................. 36 Calories
Explaining why you got out of bed immediately......816 Calories
GETTING A SECOND ERECTION:
If you are:
20-29 years old........................ 36 Calories
30-39 years............................ 80 Calories
40-49 years............................ 124 Calories
50-59 years............................ 972 Calories
60-69 years............................ 2916 Calories
70 and over......................... Results are still pending
DRESSING UP AFTERWARDS:
Calmly................................. 32 Calories
In a hurry............................. 98 Calories
With her father knocking at the door... 1218 Calories
With your wife knocking at the door.... 3521 Calories
8.
 Sex strengthen muscles. So much pushes and flexions... It depends on 
your stunts in bed, of course, but it's clearly a lot more fun than 
running for miles. Bed fitness sessions clearly improve muscles of your 
pelvis, thighs, buttocks, abdomen, chest and arms. 
9. The more 
active your sex life is, the more attractive for the opposite sex you 
are. High sexual activity makes the body release more pheromones, 
chemicals that attract the opposite sex, but also to display a security 
given by experience. 
10. Sex improves senses, at least the 
smell. Following the orgasm, a rise of the hormone prolactin makes the 
brain's stem cells form new neurons in the olfactory bulb, boosting a 
person's olfactory abilities. 
11.Sex is also a pain reliever, 
ten times more effective than Valium: immediately before orgasm, levels 
of the hormone oxytocin rise by five times, determining a huge release 
of endorphins. These chemicals calm pain, from a minor headache to 
arthritis or migraines, and with no secondary effects. Migraines also 
disappear because the pressure in the brain's blood vessels is lowered 
while we have sex. So now we see that actually, a woman's headache is 
rather a good reason for having sex, not against it.
Sex also stimulates the release of estrogen, decreasing the PSM pains. 
12.
 Kissing stimulates salivation, which cleanses food left between the 
teeth and lowers the acidity in the mouth, the main cause of the tooth 
decay and bad breath. 
13. Sex fights off allergies. A good sex 
session can be a good remedy against stiff nose, being a natural 
antihistaminic that helps combating asthma and high fever. 
14. Regular sex  balances the ratio good cholesterol: bad cholesterol.
15.
 Sex balances sex hormones: estrogen protects a woman's heart but on the
 long term, it can be efficient also against Alzheimer's disease and 
osteoporosis while testosterone spurs the growth of the bones and 
muscles. 
16. The sexual activity means less colds, flu and 
infections. 1-2 intercourses weekly means 30 % higher levels of the 
antibody immunoglobulin A, that spurs the immune system.
17. Sex means a better control of the bladder, as pelvis muscles controlling the urine flow are stronger.
18.
 After orgasm, especially in the evening, we get sleepy. Sex increases 
sleep quality. Following an orgasm, the body of both males or females 
becomes completely relaxed, so they may have a good deep sleep.
19.
 Most pregnant women stop having sex a few weeks before giving birth, as
 there is a widespread idea that having sex late in pregnancy could 
trigger labor. But studies shows this is not true. Prostaglandin is 
released in huge amounts by the woman's body as it triggers labor. Also,
 orgasm can induce uterine contractions. Still, there is no scientific 
proof that sexual intercourse close to the end of pregnancy starts the 
labor.
20.Sex fights cancer! Various researches have shown that a
 high ejaculation frequency and sexual activity are linked to a lower 
risk of prostate cancer later in life. A study found out that men who 
ejaculated 13 to 20 times monthly presented a 14% lower risk of prostate
 cancer than men who ejaculated on average, between 4 and 7 times 
monthly for most of their adult life. Those ejaculating over 21 times a 
month presented a 33% decreased risk of developing prostate cancer than 
the baseline group.
Researches found that sexually active women have a lower risk of developing breast cancer.
Many
 cancers can be boosted by impairments of the hormonal balance, and 
perhaps sex and orgasm can fix this. Indeed, increased estrogen levels 
have been linked with higher risk of many cancers and increased 
testosterone levels in men has been linked to greater risk for prostate 
cancer. 
But too much sex can be harmful for your health. In 
fact, over sexual partners increase the risk of infection with 
papillomavirus (HPV), a common genital virus, which can be transmitted 
even through anal and oral sex, by 8.6 times.
The human 
papillomavirus (HPV) is the leading cause of cervical cancer (in uterus)
 (95 % of the cases). Due to oral sex, HPV can provoke larynx, esophagus
 and oropharyngeal cancer (cancer of the throat, tonsils and back of the
 tongue), in a rate higher than heavy smoking or alcoholism. This virus 
can also provoke periungual skin, vulva, vagina, penis, perianal and 
anus cancer and it is also suspected to cause breast cancer.