There are several types of wheel, but no matter what the size of your wheel or the quality of your rubber it's always more comfortable riding on smooth terrain. Avoid bombing it down a paved road and weaving your way around stones, potholes, roots pushing up through the asphalt, manhole covers, furrows, tarmac joints, sleeping policemen, etc. Basically, use the brakes when you're passing any gravelly or bumpy surface–and other features of the road that you only really notice once an ache has already set in. Riding a scooter in parks and gardens is tempting, but don't forget that scooters are primarily an urban means of transport for gliding over a smooth surface. With a classic model, there's no way you could go for a ride on bumpy terrain. So if you're interested in trekking around parks, get yourself a different model.
In short, when it comes to pain the winning trio is the right position, the right scooter, and the right route. It's child's play!