One of the most important lessons one can learn in being generous to others is that handicap spaces are there for a reason. They're not just another free spot that you lucked out to find, that might cost you a lot of money if a parking enforcement officer sees you. They make a challenging situation a little bit better for a lot of people. It's also vital to realize that these are real people, not just some hypothetical other. Most important, don't judge those who do need them.
Some disabilities aren't so obvious as requiring a wheelchair. It's quite an ordeal to make your way in the world with a prosthetic, for example. But many people do just that, with an artificial leg invisibly assisting under a pair of jeans. These men and women are just as deserving of a shorter walk as anyone, but you might not know it. If you don't already know these things, take a lesson from this video.