Well compared to many of super athletes here it may not seem that much, but my wife and I celebrated putting in (over) 1000 miles on our bikes this fall. In addition to the American flag, we rode every mile with the blue ribbon prostate cancer flag to spread the word about prostate cancer. It did it's job as people asked us about it during the SAG and other stops. We even had some high fives when we rode the blue "accidentally" in a field of pink during a breast cancer walk.
The point is that we all must try to do what we can. If you are an ironman (or an ironwoman like my wife) or a marathoner, that is great. If all you can do is get up in the morning, then that is something to celebrate! Focus on what you can still do. For me, I can only do a fraction of what I could do two years ago. But I take pride in what I can still do. (The only thing I am better at since getting cancer is sleeping and resting.)