it depends on what time of the day it is. i feel younger in the morning (birthday this month - will be 44).
sometimes, like torp, i think 'have i really accomplished anything'...but if you have a family you are doing two things at once. some months i have a lot of music in memory, and then once in a while family priorities take over and i have to put it off a bit. one thing i do find, is when you learn something musically (and it stores in long term memory) you don't have to keep practicing that particular thing over and over anymore. also, when you love something, you do it no matter how long it takes. i have determined that if i need to crawl onto the stage at 90, i will. i'll use my cane to prop up my body from the back, and if i fall forward that's ok (will look better musically).