Sometimes, nothing feels better than executing a good hard kick. In general, your legs are much stronger than your arms. So striking with your foot has the potential of being able to deliver much more force than a strike with the fist.
Before you plan to kick anything, however, you’ll want to understand where your current effective kicking height is. The final point of a kick should be determined by the direction the knee points to. So in the illustration to the left, the knee is pointing downwards, maybe at the level of someone else’s knee.
Test your own kicking target options. First, lift up you knee to a height you can keep it at, bringing your foot to the opposite knee. Can you balance at this point and remain stable?
Next, extend your leg, keeping the knee stable in one point in space. The lower half of your leg essentially pendulums from the knee until the knee is straightened.
Now notice, when you straightened your leg, did your knee drop at all? If so, then you most likely need to work on your hamstring flexibility (the large muscle on the back of the thigh) and possibly your quadriceps strength (the large muscles on the front of your thigh). Find the point in space in which you lift your knee and then straighten the leg without dropping the knee. This is your current kicking height and it indicates the height at which you can deliver effective power.
As you work on flexibility, you’ll be able to execute a higher kick. As shown in this 3rd picture, this kick is higher, but is still stable – here the knee pendulum the kick while approximately at belt height. And while you shouldn’t stand there like a statue after you kick (like I’m doing for the photograph), you’ll develop your kicking muscles better by practicing this posture.
So, know the difference between an intentional, stable kick versus simply flinging your leg. You might be able to fling your foot up to a higher spot, but it will not likely serve you in terms of delivering any effective force to the target. Know your own range.