You're talking about things most others experience, so I'd not go as far as defining you as a wreck, although it probably feels that way.

The way I see it (as an older person) is that you can clearly see the issues you face and that means you have the ability to make changes as needed/required. You said you're enjoying the challenge of working towards overcoming the issues and that's good, having a compelling why will help keep you motivated and on track. Other issues will arise and you'll need to address them in the same way. Some may break you, and that's when you have choices to make.

Aging doesn't mean life gets worse. In fact, as I alluded to, I've never been (overall) better than I am now. Sure, there's been times when one element of me may have outshone the others, but aging well, doing it right, can certainly make a person feel more complete.

Society lives a more sedentary lifestyle these days. We don't need to tend gardens, chop wood, mend fences, milk cows, build our own stuff and so on...it's conveniently provided and so we aren't moving about as much. As you (anyone) ages though, the movement is critical to health. Sitting is the new smoking, they say. It's something to think about, along with internal development as well. Time doesn't guarantee wisdom, one needs to seek it.

As for your colleagues (anyone) perceiving you as young and newbie...I get it. Best just to do what you do, as well as you can, and forget what they think. Your actions and results will demonstrate your quality better than your words could explain it. (Not that you've been explaining it, just a general statement.) Be the best you, the rest will fall into place.