I'm 33, slim, in decent health, not overweight at all, for about the past year or so, I've been experiencing some erectile dysfunction. Not entirely, but basically what happens is I can get an erection if I'm turned on or if it's been a while since I last ejaculated, but I have trouble maintaining the erection during sex. I notice that it might start out fine but then about half way in I'll get somewhat soft or even totally soft then get hard, and back again.