Idealism, as "noble-mindedness," is the belief that we should always strive for our highest ideals. Sometimes, though, idealism is a sort of incurable optimism.
It's one thing if you always pursue high-minded goals and right conduct — one definition of idealism. Just be careful to not get so caught up that you fail to see things as they really are — you don't want to go through life "wearing rose-colored glasses" — yet another definition of idealism. In philosophy, idealism is the theory that ideas are the only reality.