Along with exercise what are the best foods to eat to maintain a healthy strong long lasting erection for having sex?

Herbs more helpful. I advise a healthy diet rich in fruits & veggies. Avoid food with gmo's. Many herbs are well-known to improve male sexual function. Some of the best choices are ashwagandha, maca, ginseng, tongkat ali, damiana, fo-ti & gingko. Besides herbs, l-arginine, zinc & seanol ( a seaweed) extract can be very effective. See http://altmedicine.About.Com/cs/conditionsetoh/a/erectiledysfunc.Htm.