I was riding until I crashed hard, kept falling and went into HE phase. Now I'm scared to ride, but I go to Y once/twice a week and ride stationary bike. Can't fall off that one. Do what you want until it becomes impossible is my advice.
The problem is you shouldn't get very tired. Weakening the organism in general works in favor of infections/virues. On the other hand stef2011 said you need to do regular exercise but an easy one like a longer walk or something like that to help natural immune response.