The only way I know works and I do it, is "speedhack" When you sprint, you will end up with max points you can get in one round before it becomes a "diminishing effect"
Get yourself overweight, sprint with speedhack, get max xp possible, repeat on next raid.
Yuou can also do it crouched and proned.
When I started my new account, at one point I was on lvl 7 strenght and 5 stamina due to always picking up everything I found at the time.