Ejaculation does tire you as everyone knows, so its a good idea to ejaculate not so often and only at certain hours of the day, for example at night just before sleep so you get tired on purpose to help sleep.
Also, if you masurbate but avoid orgasm at all costs, the results are the oposite, that is if you can control yourself not to reach orgasm, if you do this what happens is that your energy levels goes up instead of down, so instead of feeling weak you are feeling strong and powerfull, and not only that but it has also the effect of relaxation, and many other side effects wich are not harmfull at all.
Basically, what you should do is breathe deeply while you do "it", and whenever you feel you get close to orgasm you stop until you dont feel so close anymore, usually a few secs the first time, but the more times you get closer to orgasm youll notice that it gets dificult to stop on time and the time to calm down is longer, thats because of the energy that is building up. With practice youll be able to store much more energy.
One of the most important things about this technique (besides self control) is to be able to move the energy that builds from the base of your organ to go through your body to your brain and back to the body, this may seem weird, but i suggest you to try it, you can feel this energy and direct it with practice, imagine that some kind of purple smoke is acumulating in the base of your organ, or imagine that this energy is electricity, and when you take a deep breath feel and move the smoke or electricity up to your brain, and when you exhale the smoke or electricity goes from your brain to the rest of the body, you must feel this smoke or electricity or energy flow in your body.
The longer you build energy with masturbation, the more energy will be flowing all through your body, but you must avoid orgasm to keep this energy in you, if you reach orgasm the energy goes away.
Heres a past thread on this subject:
[Adult] Masturbation as a tool for growth
Heres is a good resource on this subject of energy building:
SEX AND REJUVENATION