Thankyou both songsofdistantearth and fiveelementtao - both extremely important revelations. I find that alot of men's erectile issues are psychological, cetainly at age 25. My suggestion is get out of your head (the upstairs one) and get into the downstairs dept - stop thinking about it too much!
I have also found with many men, that once they enter into this work (whether the kundalini route or the Taoist route) their bodies' begin to respond to a more "conscious"way of lovemaking - follow your body's needs and requirements - don't force anything to happen, and go slow. Simply respect the process.
In terms of exercise - I find squatting the best for powerful erections and longevity in the lovemaking arena. The squat should be perfomed differently from a regular squat where you would normally engage your glutes to lift you up. Try and use your Hui - yin (perineum) to pull you up - visualising a LONG length rising from there all the way up your centre towards and out of your head (like a tree trunk). I would say at this point to work with Taoist self-cultivation methods (including testicle massage)- with ejaculation only 1-2 times per week.
Witch is correct - fish oil fish oil and more fish oil. Fresh ginger is also recommended - trash the pizza