I'm coaching a mixed age hockey team (age 18 up to 50). I'll start with a jog for about 10 minutes, followed by a flexible stretching period during the jog (High knees, high heels, cross-over passes, knee-bends followed by jumping up, swinging the arms forward/backwards. So that all muscle groups are activily used. This takes max 15 minutes. This is followed all kind of exercises with stick and ball. People who need to stretch more, can take then an additional 2 to 3 minutes, while others are busy with stick and ball.