How can I stop acting like a spoiled brat?

Well first keep in mind that wanting pretty nice and new things isn't a bad thing. It's how you've frown up, it's perfectly fine to like them. If you don't have to work I agree you should volunteer somewhere. Maybe even on an expedition that requires money to go, do one of those aid trips to a far off location. As for outdoors start off slow, go on a camping trip in a park, not the full out wilderness. Try complementing friends when all the attention is on you, avert the attention on occasion. You're a product of how you were raised, but you can use these privileges to help others. If you're a socialite and people like paying attention to you throw a party where people donate to a charity instead of bring you gifts, the small things you know?