Changes in my strength in various levels between physical to mental over my 30s

It's already been only one year left for my 30s.

Over this period, I experienced many changes in my condition, many levels between physical to mental.

As you may imagine for a typical men in his 30s, my pure physical strength has been lowered, which I hate to admit but I have to do.

In some levels I've lost a little just as my pure physical strength has been as I mentioned now, in some levels, I've lost much, and on the other hand there are levels I've gained a little and even there are a few I've gained greatly.

To describe this, I'll list up some description which reflects the change in my condition over my 30s.

• Pure physical strength was on the decline. Now I can't imagine myself running a half marathon with the time around 1h40m (100 minutes), which I achieved around the age of 30.
• With being conscious of the core of the body, I feel I can run and throw with less effort than when I was 20. Till I became 30, my form of throwing, running, and skiing was incredibly inefficient. To make these movement effectively, you should bend each joint to make entire body a mild curve. Instead, whenever I saw my form, I see myself with one or two part of my body was excessively bent and didn't look smooth at all. Now, I'm a little bit conscious of make my entire body bent gently to make the most of my physical strength.
• This is what I think I've lost the most. Sometimes I feel so week that I can't even sit smoothly, let alone standing, and feel it would be helpful if I had a stick to support my body. This is likely happen after I was under a pressure at work over several days, or after I was engaged in important computer work.
• I do things at the pace ordinary people do at work, but in weekend I find myself doing things or speaking only a half as fast as I do on weekdays.
• It's consistently been difficult for me to have fun in having conversation with people of the same generation or younger people.
• Since I was in high school, I had been worried about this difficulty to have fun, and sometimes made me really unhappy and miserable. I had wished I could have had fun just like other young people, and this desire had seldom been fulfilled. In recent years my stance has been changed although I continue to have a difficulty to have fun in a way typical young people do.
• In recent years, I've become aware that I can have fun, even though it may be quite different from typical people of my age group, which make me feel at ease much more greatly than ever before. Even now, I sometimes feel still lonely when I can't have fun as other young people do, but now I have become much less miserable.
• After I became 35 years ago, I began to feel much pleasure when I was able to contribute to something or someone else. Sometimes, this sense, and rise in self esteem makes my fatigue (I've just mentioned this in the third item of this list) feel much less painful.

I'm not sure If my condition is improving or going worse, but at least I kind of enjoy to watch for and analyze these changes along aging, which relieve me of some pain from the stress or the decline of my physical strength.