Make sure you commit yourself to a 100%, all out high intensity workout session. This works even better if you can do this with a training partner who can be there to push you through the temptation to stop and rest. The more types of kicks you can incorporate into these training drills, the more of your muscles you will work and more moves your body will commit to muscle memory for use in the heat of a fight.
Try incorporating front kicks, side kicks, sweeps, round houses, spin kicks, butterfly kicks, axe kicks, jumping kicks and crescent kicks. You can also add in some knee strikes to break up the routine now and again. You will possibly find crescent kicks the toughest part of these kicking drills. Use both inner and outer crescent kicks to a target, preferably at least head height.
All exercises should be completed back to back without a break, making for an incredible cardio session. Each type of kick should be completed in a gym style set for maximum effectiveness. For example, for crescent kicks; you should do at least 50 reps (kicks) for both inner and outer kicks and with both legs. All these exercises can be just as effective without hitting padded targets or heavy bags. Try paper or clapper targets instead.
If this still isn't enough to wear you out then you can add in some kick combos for practicing some real life techniques. And for the true warrior, finish the hour off by doing some sparring, but only using legs and kicks, no hands.