I completely get what you are saying! I'm on day 8 of a break right now and the way I feel at this very moment I'm not even close to ready to go back. I'm not going back until my body feels good.
As for vowing to never get old...I did as well. However I'm getting a serious education on the laws of nature and at the minute I'm giving up turf I thought I had claimed forever.
Its hard to take that mental switch and flip it into "rest is ok" mode. I think the guilt driven rationalization that takes place is amazing, "well, I can just do abs and pushups maybe?" "A few LIGHT sets wont hurt"... all that does though is deprive the body of something you obviously need - TRUE, ALL OUT REST.