Here is one of the [tag]football conditioning drills[/tag] we do that is not only good for conditioning but also concentration, not to mention camaraderie.

Split the players up into classes–9th, 10th, 11th, 12th or however you wish.

Sprint ten yards and put one arm on the ground and do a complete circle then switch arms and go the other way.
Get up and sprint 20 yards and do either ten push ups or sit ups.
Get up Sprint 30 yards pick up a football and look straight into the sky with the tip of the ball on your nose, then spin around ten times.
set ball back down on the designated spot and jump three times over a white line or the [tag]football[/tag] emphasizing keeping both feet together. (This is fun to watch and the kids really enjoy it because their equilibrium is off and they have a hard time jumping over the line or ball.)

Finally sprint a final 20 yards.   Definitely a fun football drill for everyone involved.