How do you regain the loss passion - enthusiasm in things?

Pre-infidelity- im inspired to work. Use it to advance my career aton and this what gave my family the comfort we are enjoying.

Post Infidelity - everything feels like a chore. Im so bored/ dont feel like studying. I just feel tired and would rather play games or just lie in bed. I worry things will caught to me and may affect my current career.

How do i get out of this slump? The good thing that has happened to me personally is i become active in Gym.. the rest (professional) has been a downhill.

Any advise is appreciated.

Thanks