Today my father called me, complaining about depression, low motivation, sex drive, body aches. His doctor doesn't seem to want to help, even with getting bloodwork as he said it's "natural aging" lol. My dad doesn't want to take testosterone either at this point yet, so is there any natural supplements that can help him increase his testosterone. So far I've come up with vitamin d and zinc. Does tribulus work ? Even if he can raise his levels a bit to feel somewhat normal again, he's not looking to bodybuilding etc just a quality of life. Thanks