Although, many of us know about this context yet their is a need to explore more of what it is.
Admittedly, the most powerful energy is the sexual energy as suggested by the fact that the whole life form existing on the planet is result of this energy. Doing sex or masturbation gives rise to sexual energy and develops it and when this energy is discharged so is sexual tension, as a result body feels relaxed. This is indeed an important thing to release the sexual tension otherwise body would not be able to focus on other goals. The tension produced can also make body mentally and physically tensed resulting in muscle tightening which is not at all good for health since when muscles tighten up they hinder breathing process and muscles would not get proper room to grow.

WHAT BODY EMPHASIZES ON?
Testosterone is the male principal hormone that regulates many essential functions of body such as sperm count, libido(sex drive), muscle growth, bone density and so forth.
However, body priority does matters as testosterone does not works like what most of the people think. It works on what body needs i.e. what central nervous system emphasizes on. The number one priority of human body is breathing then mastication(chewing), next one vision and hearing and so on. These are more prominent to body after that body takes precedence over functioning of different body organs. The long way after, it lays attention over reproduction. Surprisingly, muscle building is the last priority of body. But most of the people trick body to emphasize only on muscle growth by not having sex or masturbation.

But this is what is more harmful
since it will result in sexual tension

MYTH BUSTER
Body prioritizes sex or masturbation over muscle building. Recent researches have also shown the same and one more surprising fact is that doing sex or masturbation infact increases the testosterone levels. A good sex gives body a rebound so that body can increase the overall growth rate and body releases dopamin and serotonin hormones(regulates happiness). It does decreases cortisol levels(stress hormone). And when body is happy everything goes well and smooth.

Doing sex or masturbation does benefits the body resulting in more testosterone production in body.
This does not decreases the testosterone levels or growth rate.

The percentage of sperm in semen is only 2-5% , their are other fluids as well such as water, seminal plasma etc. Even semen ejaculated has a very little amount of sperm. Body has its own stock of testosterone and sperm that body utilizes for other prominent functions like immune system, bone density etc. Body has enough count of testosterone, it is not affected by one time ejaculation of sperm. Another myth prevalent is that body takes 24-48 hours to regenerate testosterone or sperm which is totally insane.
Although, body produces sperm everyday but it takes 64 days to produce a full new sperm(spermatogenesis). In context of testosterone body keeps making testosterone in cycles at different rates. Since body can not stay out of testosterone as it has to maintain other functions as well.

Then why we feel lazy?
ß. After orgasm(sexual activity) body releases oxytocin along with serotonin and dopamin that relaxes the body, makes us feel dizzy or lazy(weakness).
ß. Also, after the sexual activity semen is excreted out along with which a significant amount of zinc is excreted that is also considerable factor for body feeling weakened or energyless. Fortunately, this is a temporary stand and lasts for 10-15 minutes.

If you have proper and top quality nutrition body will recover zinc lost more quickly

SUGGESTIONS
#. For a regular person(with no serious health goals), their is no problem in performing sexual activity 3-4 times a week since it is normal and will boost testosterone levels and make your life more happy, the only thing is be careful about your diet. But if you are already in excess situation like, 7-10 times a week it would rather be more malicious for your health.
#. People who have serious body building goals, what impact will sex or masturbation have on them? Body builders or sportsmen need to be more careful, however, sexual activity also hold as importance place as do other body building goals. Equipoise should be maintained in life. For body builders, you need to have a gap of 5-6 hours between your sexual activity and workout in order to make body prepared to hit the gym or do exercise. And doing sex 2-3 times a week is totally fine. In case you exceed this limit it would pose problems for you, perhaps you will start worrying about your goals thus making your body tensed. It would rather harm you more internally and intensely.
*If you are in bulking phase or gaining phase performing sexual activity 3-4 times a week would not be a problem since your body already is in bulk i.e. having enough nutrients to help you recover more quickly.
*And if a person is in calorific deficit it is totally prohibited in this state to do sex or masturbation and even if you want to do you would not be able to since in such state your body is running low of sperm, testosterone and libido. But this is temporary and you need not worry at all because this is normal.

SO HAVE LESS CUTTINGS IN YOUR DIET TO PREVENT YOURSELF FROM STRESS AND HAVE SEX FREQUENTLY TO BOOST YOURSELF AND TAKE CARE OF THE CAUTIONS