Not so much running, but doing alot of walking. Do this with a pack that weighs what you will carry on a typical game day weighs.
Being a scout - here's a typical outdoor game for me. Walk 15 Km, but drop to prone every 100meters, look and listen for 45 seconds or so, report to commander, repeat 150 times. A wee tireing at the end of the day.
Depends on how you have to play. Some guys at our games walk 500m get in a 8 hour gun battle, then walk back to their car.