I would presume you are a top, since you mentioned taking Viagra.
I used to be able to get hard in a jiffy, but that is not longer the case as years passed.
Perhaps you need to re-evaluate your priorities, needs and expectations. I used to go to gay saunas and have sex with a few bottoms. These days, I go there to relax, and if everything works out, I may end up with a man and if sex happens, it happens. But all this is explained to the opposite party first. Even if I do not end up penetrating the partner, I make sure he is not left high and dry. I try to satisfy him orally, or with a prostate massage, or a combination of both and more.
I have not started to bottom yet - I have met older men who were tops and had now decided to bottom in order to hook up for some intimate times.
So now my priorities are to relax, and if I manage to hook up with someone, I will see how far I/we can go. Orgasms are a bonus. Thinking of, and expecting to top, may add stress to yourself - you probably are aware that stress is a boner killer.
I hope this helps, and I hope you get to have lots of fun, pleasure and intimacy in different ways.