1- Cry (yes, that is ok) 2- Get so angry and sad that you want to punch the wall. 3- Put the best motivational music you can get and hit the gym 4- Channel all of that anger and do your routine with 10% more weights. 5- Talk to that beautiful girl in the gym after you finish your set.

Repeat this processes as many times as necessary.

Source: I just did this.

Optional: Friends help a lot during these times.