If you look at your map, you will notice some star icons. These particular icons indicate Survival Training challenges that can be completed for huge PP bonuses. Each of the challenges will require you to kill a specific number of enemies with a specific type of weapon or vehicle. The catch is, you only have a minute to complete the training sessions. Many of these challenges can be completed using The Rollerhawg to quickly flatten your foes. The more challenging unarmed training sessions can be completed using the unarmed bonus damage book and knee drop combo. If you're having any issue with completing the Survival Training, there's a really good guide here detailing them further.
Note: I did not create the below, linked guide.http://www.neoseeker.com/dead-rising-3/walkthrough/Survival_...