#102-1. Humanity as a whole must learn to leave behind the "you or me" attitude of the past and begin to make the "you and me" or "you and us" attitude a total reality today!
-Thomas D. Willhite
#102-2. Regret for the things we did can be tempered by time; it is regret for the things we did not do that is inconsolable.
-Sydney J. Harris
#102-3. He who adds not to his learning diminishes it.
The second one is a killer. Anyone who is not "very young" would relate to it. I can offer this advice to such persons: Let others who are younger not suffer the same pangs, facilitate their stepping out and beyond, their experimentation and help them boldly go where... you perhaps did not go.
Knowledge and skills can easily "rust" if not updated and practised. A useful habit is to listen to or read something without saying, "I already know this." Often we discover a new interpretation.