Relationship between sport and nutriton and sex?!

Doing a lot of sport activities and having a perfect nutrition before age 25, does it help in making you much stronger and having much
energy in sex later even if you did not have to keep working out As much as in your earlier years? I'm a 24y/9m male and I have lived a normal life during my past years as any modern guy but lately I have started thinking about this weird idea that if I had more and more of the above I would have a better sex life and in the future after having a long day at work, I will still be able to satisfy my wife completly without spending a time( which may I don't have) in workingout just to keep my energy and power in the normal levels. I started masterbuting lately and I noticed that I need a longer time to get another erection ( a little bit over 20 minutes) and longer time for a third. The quantity of sperm is not that much and get less with the second and later times. I'm overweight and I have not do any workout other than normal day working during past two years because of college then work. Is this will affect me on the future and is there any thing I can do during this three months before age 25 to get the perfect and strong sex life in the future without having additional efforts in later years? Thanks in advance :)