shuttle  runs i have found are great,work out a square say covering from the side line to the posts out to the 30m line set out markers and at each marker have some thing to do like fist marker 10 pushups 2nd marker 10 situps 3rd marker dive on ball,playball sprint to 4th marker hit ground crawl on belly to 5th marker skip rope to count of ten sprint to 6th marker tackle bag and so on than sometimes run them in tows and get them to leap frog each other that get them really going.do some boxing on a tackle bag for 15,30 seconds what ever you thinks will help.