[W]e can look at overall trends in the scientific literature and draw some conclusions about what facets of your life are likely to influence your fertility.
What Will Likely Affect Male Fertility
According to a 2015 review, “It is clear that marijuana and its compounds can influence male fertility at multiple levels.” Specifically, marijuana can cause decreased sperm density and low motility…
Several studies have found that both sperm quantity and quality suffer when a man is exposed to stressful events.
What Is Not Likely Affect Male Fertility
Frequent sex (including masturbation)
If you were ever told to avoid masturbation or sex lest you “run out” of sperm, I have some good news: that’s almost impossible. A human man produces about 1,500 sperm cells per second…
While heavy drinking is implicated in fertility issues, light, moderate, or “social” drinking does not appear to be. As one researcher put it, “It appears that moderate exposure [to alcohol], to the degree experienced by the general population, is not sufficient to account for the infertile state.”
So, if you’re trying to conceive, it may be a good idea to skip the blunt, loosen your trousers, and take a shower rather than a bath.