Why man? It's natural to have different phases of life... As an example, I remember that wonderful period when I first was with my wife. That excitement, not being able to keep our hands off each other, going at it all the time. Now we have been married 16 years, together for over 20. Of course it is not like that anymore. But really, who would want it to be? Our sex life is still amazing, but of course different. We are both more skilled and know each other so well, but just busier and less energetic after both having difficult careers. (lawyer and doctor). We go at it once a week on average and that is good for me. I am lucky in that she is accommodating when she is not really that into it
Would I trade her for a Hot, rarin' to go 19 year old? Of course no. Maybe that would be a novelty for a week or something, but the reality is I could not give her what she wants and neither could she for me. Some guys I think try to pursue that to make themselves feel young. Maybe it works I don't know.
Of course the health decline in aging is a bummer, but we want to do different things. Slow down, do some traveling, talk, spend time with family. Essentially grow old together and end up in those matching plots. I wonder dude, if you are religious at all? That would definitely change the way we each look at this...? I see it as still moving towards something after death that is even better. If you are not, you might see it is a depressing finality, something that is gone forever...?