It's hard to explain. Everything just gets harder.
New medical problems appear, body fat becomes harder to lose, gray hairs appear, friends raise families and move away, family members die, and you often have to start worrying about the mortality and welfare of your parents.....as they are either elderly (or at least "old").
And your mental status changes too. The older we get, the harder it is to change. Older people became set in their ways, and struggle to adapt to new situations.
Looksmaxing is harder now. It requires more time and effort to look like I did 10 years ago.
People are also pretty prejudiced against older people, in both the dating world and job market. It's tough.
There are benefits though. Old age (up to a point) often provides us with greater experience and self-awareness (which I like), but is it worth the trade-off for youth, beauty, and vitality? That's hard to say.
I would say though, that I most liked myself as a man in my mid-to-late 30's (age 33 to 39). I experienced high mental clarity, and the benefits of top tier physical strength....without the major indignities of old age.
If I could set my physical and mental clock back by 5 to 10 years, that would be nice.