Talk to your doctor and get Cialis, should do wonders if your problem is physical and not psychological. If the latter is your case, then you will most likely need a shrink.
In a way with all these people coming on here asking for sex help I feel lucky! At 47 years old I got no problem keeping up the wife's current 2X a day routine and heck on weekends it can end up being 4 to 6 times a day.