Tom,
I think many (if not most) of us have felt something of what you expressed -- being reminded of our own mortality, wondering if we'd ever get to retirement, etc. I definitely found that going through cancer treatment changed a number of things about the way I viewed life and how I spent my time -- and most of those changes turned out to be for the better! Like you, I had certain goals as to what I was going to do in retirement, but once I realized that I might not get to 60 or 65 (I was 39 when I had cancer), I started refocusing on what I thought was most important to do now in whatever time I do have. For me, that meant scaling back from a 60-70 hour workweek to a more manageable one so that I could begin to make room for other things that really matter to me -- and the end result is that each day has become more enjoyable. The list of "other things" filled up over time to include volunteer work, singing in a choir, playing the organ (a skill I learned post-cancer), gardening and growing orchids, and traveling with my husband to parts of the world I thought I'd never see. One day I woke up and realized I had turned 55 and was eligible to start taking early retirement benefits, but I'm not ready to consider myself a retiree quite yet.
I'm glad to hear you've been able to get back to teaching (and enjoying it). Even though you're now a couple of years out from the end of your treatment, I suspect you'll continue to see further recovery as you go along -- I was amazed at how much improvement I saw well past that point.
Stay strong and please keep in touch.
Cathy