Hi Jayak,
I am within a few years of you in age, and have accepted the fact that I cannot do everything that I want to or used to. If I am unable to do a two mile portage over a steep mountain trail, I will not do that route and will choose another route to paddle. If it comes to the point where I am unable to portage or hike into a particular wilderness area, though I have enjoyed that area in the past, I shall choose another area that I can handle and enjoy the memories of the spot in the wilderness.
Wilderness areas are special. With the housing developments and deforestation that you mention, the truly wild areas are becoming even more precious. The Wilderness Areas that are set aside by our government are not amusement parks for our sole use, but a place where nature may rest with minimal disturbance. The wildlife and biosystems of those areas are only part of what wilderness areas preserve. It also preserves the spirit of the land.
The wilderness areas also provide a baseline of comparison for what our society does. Consider humans and their actions an experiment, and all properly run experiments need a control group. The wilderness areas are that control group. They gives us a point to measure our current standing against what has been and a chance to see if we have bettered or worsened the world. That is another reason why we should not damage the remaining natural areas, lest it changes our baseline comparison.
Yes, we age. We are not always capable of always do the things we wish; the acceptance of that fact is one of the signs of maturity. We can not always insist that the world bends to our individual wants; once that acceptance is achieved, life can become broader, not more limiting.
Paddle smoothly.