Mono is a big time serious disease. Grown-ups can die from it, and recovery may take years.
I had it when I was ~20 years old, I was completely out for over a month, very touch and go whether I should have been hospitalized. And, I could still feel after-effects for more than a year later. There were some days I woke up and was just woozy, dizzy and not able to focus or be productive at all, lost day.
A doctor I talked to had a colleague who got it as a grown up, obviously. He was away from work a year.
So, if Cyancapsules is reading this. Have a good recovery and take care of yourself. Do not try to overextend yourself, it will take its time and can't be rushed.