One of the core beliefs of Stoicism is that you control yourself and nature will take it’s own course. This means that you can’t necessarily control the circumstances you are put in, but you can make the best of them. I think right now we can all agree that the external circumstances are not optimal.
Individually we cannot make COVID disappear but as an individual we can chose to make the best of the situation we are in. For some people that will mean working on their weakness. For some marathoners, for example, that could mean trying to get more speed by trying to get a faster mile or 5k PR. For others, it could mean trying to become more well rounded by incorporating strength or mobility exercises.
Others may double down on what is already working for them. Without the “deadline” of a race you may be able to spend more time focusing on what is working instead of trying to fit it into a race build-up. Finally, others my experiment and try different training methods. The pressure of investing time in a new training plan and it not working out has been lifted and you are now able to experiment on something you have wanted to try.
We can feel bad that “live” races are few and far between right now or we can accept it and decide that we as individuals decide what kind of runner we want to become. A race does not make the runner, a runner makes the runner.