Swinging your leg at a target is a lot of fun. I've been playing with the kicking motion for a couple months now, we have a bag hanging in the yard, and I recently strung this little fella in the gym. I don't have any structured training for kicks, I just throw a few between sets and a few more to keep me moving throughout the work day.
I'm astonished by how fast I've improved. When I started, it felt likely trying to catch a ball whilst drunk. Now, my left feels more coordinated than my right did a month ago.
I've strained my groin trying to kick too high as few times, added flexibility would be useful. But for now, I'd at least feel confident in head kicking a toddler.