Place 2 cones 10m apart. With a running clock, sprint 10m in the 1st minute, sprint 20m (10mx2) in the 2nd minute, sprint 30m (10mx3) in the 3rd minute, etc, etc. Continue in this fashion until you fail to achieve the required number of meters in the appropriate minute.

Fun. It’s easy until it isn’t and then it gets hard fast. Finished 14x10m but only managed 12 of 15 in the next round. Encouraged to walk in the down time by all the mosquitos.