"I'm sure that as we get older, more experienced and our strength is already pretty good there has to be something 'extra' that is needed in order for us to get more out of our lifts…"
The main thing I think of under the heading of "getting older" is simply lack of time. From an unrelated thread, I'm now aware that Forklift is busy raising two kids.
I've never struggled with lack of motivation or lack of self-discipline --but lack of time has always been a huge problem, along with lack of access to equipment.
I can remember a period of my life in which I rode a bicycle 15 km each way, to and from the gym. Sounds like a great warm-up and cool-down, right? The problem is, simply: how many hours have you got in a day?
There was one guy who was something like a bodybuilder and/or olympic athlete who was at that same gym for extremely long hours, and his wife would bring his kid to visit him at the gym. At first, I thought that was really strange and inappropriate --but as I saw more of what the guy's schedule was, I realized that his kid probably didn't see him during daylight hours much, aside from those gym-visits.
Sadly (apropos the title of this thread) I really just expect to get weaker and weaker as the years go on --due to lack of time, and other sources of stress in my life. :-/