People with Mononucleosis can exercise, you need to avoid contact sports/ sports that can result in blows to the abdomen. When you have mono the spleen may enlarge to the point where it is not completely protected by the ribcage. Splenic injuries can result in abdominal bleeding that can be severe. When you feel up to exercising just go slow...fatigue is the limiting factor. The treatment otherwise is for symptoms ie, bodyaches, fluids, nutrition and analgesics. Additionally, quite a few people will develop an underlying strep throat as well. Treating your CF is always paramount- do your physiotherapy, percussion, etc. A small percentage of people can develop a longer illness similar to chronic fatigue syndrome but that is not all that common in younger (<35) patients. Most can return to normal activity in about 6 weeks.Good luck and chin up,Liza's husband