Properly trained male basketball players, 5 foot 8 inches tall and taller, should be able to slam-dunk at the junior varsity level of high school basketball.  Proper physical training is strenuous but not injurious.  Developing flexibility, strength, and stamina are the most important things an athlete can do for themselves and their team. 

Dave Lemanczyk, professional basketball strength trainer, says: “The most popular mistake an athlete makes is training with resistance before bodily leverages are optimized.  You need to develop optimal flexibility THEN add resistance to specific movement tasks.  Body building can be detrimental to a player since ballers are advanced movers.  Simply put, if an athlete trains with resistance before developing flexibility, he/she risks great injury.”
  
Cross-training can help you achieve great flexibility, strength, and stamina.  Enroll in martial arts, consider especially karate.  Train with the swim team, train with the soccer team, train with the gymnastic team, train with the football team.  Train with the dance troupe, train with the cross country team and wrestling team.  The point is your coach should never need to pull you from a basketball game because you’re physically exhausted.  And by the way, it is completely unfair to your coach, and your team, to make the coach waste precious practice time building up your strength and endurance.  You must take responsibility for your own health and your own physical training.  If you report to your sport in shape, it allows the coach to teach, which gives you and your team the opportunity to more fully enjoy your sport.  When you’re healthy, flexible, and strong you are less prone to injury and also enhance your learning capacity.  Smarts ain’t never hurt nobody.  Study like a demon, no matter what your age. 
Something else to increase your smarts, your flexibility, your strength and endurance, your health, and even your personality, is sleep.  Sleep is magical.  All humans, especially athletes, need to recover and rejuvenate.  A body needs a minimum of seven hours of sleep every night, even you!  This is what's happening while you're sleeping; at the cellular level your body is a-huffin'-an-a-puffin', so you can wake up refreshed and renewed, as long as you’ve gotten your seven plus hours.
 
There are really only two types of water that should ever be ingested; water from a good Reverse Osmosis system in which the membrane is regularly maintained and Distilled water.  NEVER, EVER, UNDER ANY CIRCUMSTANCES, DRINK TAP WATER!!!!!!!  All bodies, especially an athlete’s body, need to be hydrated.  Tap water cannot, does not, and will not, accomplish this very basic and essential need.  Tap water and well water should be classified as poisons. 

An athlete’s diet is extremely important.  The problem with a coach giving general diet tips is simply the vast majority of body and blood types.  I do however have some information I’d like you to consider:  Canned, prepackaged, and restaurant foods, provide less nutrition than properly prepared home cooked meals.  I consult with Doctors and Dieticians in teaching hospitals to prepare diets for my athletes.  If you contact them they will tell you the information they need in order to prescribe an individualized diet for you.  It can all be done through email or snail mail. Imagine how much fun the fourth quarter is when you're as fresh as you were at the tip-off and your shots are popping the net because you’re not exhausted