Research indicates that light use actually helps mental function, but heavy use impairs it.

"light use" is less than five joints' worth per week.

I can't speak to the sperm count thing, but "burnout" is a real phenomenon. It differs from person to person but you can enlist a spouse or best friend to keep you in line if you feel like you can't gauge it yourself.
TheSmokingMonkey Reviewed by TheSmokingMonkey on . Amotivational Syndrome, Low Sperm count. What I want to know (mostly from the older heads with more life experience) how do you think marijuana ACTUALLY affects people as far as being a "burnout"/amotivational syndrome and also about the low sperm count thing. I did a little research but it's almost all bullshit. Either it's whacked out hippy bullshit like "weed can cure any ailment" or whacked out right wing shit that says weed is 5 times more deadly than cigarettes and it makes your balls shrivel up and steals your soul. Rating: 5