I think it's great to always put an incentive out there when playing small sided
games or during practice. This makes the situation more intense and fun--more game like.
Keep score and give a reward to the winner or punish the losing team, say, make them run, do push ups, put the cones and goals back, or things like that.
Sure, there are times to have fun, like in this video, but keep the practice
at an intense level by implementing incentives and up the ante.