The most current recommendation I have been offered is 3-4 weeks of very restricted activity followed by graded return to activity over 2-3 months. People make fun of mono, but, there are some potentially dreadful effects of mononucleosis, including splenic rupture and Guillain-Barre Syndrome. If you wish to go against those recommendations, I can only offer you the words of wisdom I was given when I questioned the validity of some of the instruction I was being given in physical therapy school......tread lightly, my son.