Slowness in Fitness Recovery Tied In with Cancer Prognosis Uncertainty

My path to return to my previous level of cardiovascular fitness, as evidenced by my participation and finishing times in a number of long-distance races, has recently been slow, irregular and halting...causing some discouragement.  On Depot parkrun 5K Saturday mornings, I gradually increased my number of laps finished and, on April 25th, managed to walk the whole course.  But I only got through a single lap of their last race, feeling a bit too tired to go the whole distance on that one.  A couple of hours ago today I walked...at a reasonable pace...around my own neighborhood block.  On the backstretch homeward I would deliberately start some very brief, slow jogging.  This helped me gain some confidence about running.  Sometime around sunset today I'd like to try some slow running across our back yard, and see how long i can manage the effort.  i realize that i am being daily reminded of my medical status, and that the struggle to make progress...or even overcome...treatments for this unfortunate brain cancer condition is fraught with concerns about their effectiveness, and possible side effects.  I know that it's probably a good idea to be bold with my athletic training, and one of these weeks I'm going to let go at a Parkrun event and try running for as long as I am able to manage it...maybe this coming Saturday will work that way: if I tire out too quickly, I should be able to hobble over to Melissa and the car.  I don't like this cancer role in life i've been consigned to for a while.  I do know that my life...and my eventual passing through and beyond it...are in my Lord's loving and powerful arms...He brought me in and He's carrying me through it all!  I'd still like to be able to frame my own Earthly future in terms of relations with Melissa, family and friends, and athletic and intellectual pursuits.  And I'm still interested in what's going on in the world!  I can't properly boast about tomorrow(read the Book of James Chapter 4), or about the future in a personal, worldly sense...only God has the power to determine it all.  So instead, to the degree that uncertainty still maintains a vital role on this Earth,,.  I'll hedge my comments about the future with 'if the Lord tarries", recognizing that His timing is the correct timing...