only your doctor can give you that patient-specific "okay" or you will need to be cleared by another doctor. working out may not be an issue four weeks after mono but if your liver and/or spleen is still enlarged (not all people have this mono-related response) you should avoid contact or collision activities that could injury them. it takes an exam and perhaps an ebv titer (blood test) to know your state of recovery. some people improve rapidly and others do not.
when is it safe to do heavy lifting and play contact sports after being infected with mono? . i was infected with mono about 4 weeks ago. i am training to enter a police force and need to do vigorous workouts and my doctor hasn't been very revealing about when i can safely go back to working out.