Stamina

As basic and boring as it sounds, the only way to build up stamina and endurance is by performing repeated short runs with short rest intervals.

Players like Scott Parker and Dirk Kuyt stick to training regimes which work in 4 minute spells; 4 minutes at full speed followed by 4 minutes at 20% work rate - and they repeat this cycle 4 times (working for a total of 32 minutes).

Another good example is using the 18-yard box as a rectangle; sprint the long sides of the box and jog/walk the shorter sides. This can be performed up to 15 times to maximise muscular endurance, similar to that experienced on the field.