I am at the "wait and see" stage with my CLL. When my CLL was first diagnosed in April 2019, the ABS Lymphocyte count in my blood was 68.7. I continued to train for a May 5 marathon and my ABS count improved to 49.5 on May 22.
After that, I did not run as much, and my ABS Lymphocyte counts rose and then stabilized to the 64.7 to 75.4 range. In August I stopped running. (I was doing outdoor work, but it wasn't aerobic.) And on September 30 I got my worst blood test result yet (84.2).
My wife remembered something about running in Glenn Sabin's book "N of 1," so I reread it. When his CLL was at its worst, he started walking daily and then running with his dog. His blood tests stabilized, then started improving, and then they went all the way down to normal. Running wasn't wasn't the only thing he was doing. He had also been making changes in his diet.
Then I found Philip Fields book, "The Long Road Back to Boston: Running Marathons with Leukemia." My wife has been reading it aloud to me while we eat lunch. After receiving chemotherapy, he held off CLL while running over 100 marathons since 2009. His most recent marathon was on January 11, 2020.
Then I posted something on a Facebook page for people with CLL and the moderator linked to a medical journal article which found that exercise helps people who have CLL:
So you might want to gradually increase your aerobic activities. But don't overdo it; just increase gradually. The rule-of-thumb for runners training for a race is to run at least 3 times per week while gradually increasing total distance run by 10% per week.