I read back issues of Adbusters magazine for a while back in high school and proclaimed complete anti-consumerism for nearly a month. Then I got a job and had to find something to do with my paycheck.
Look to build yourself instead of buying more things and only buy necessities. Take long long walks, meet new people (whether nice or unpleasant), bring a camera along. Read more classic novels and new ones as well. Live healthily. But in the end, I guess its okay to have one or two things that you absolutely love :)