Do you want to feel fulfilled or do you want to be happy? My money is on the former; for me this fulfillment comes from continually improving.
Focus on the process. The process of learning, of working, of talking, of exercising, of being... everything you do, do it just 2% better than last time. Try and be more of yourself and less of the someone you've thought (or were told) you should be.
1. Don't go back to school; it's not a career advantage for most people anymore. You can learn more in practice than in study.
2. Find or create an active job—I mean physically active. Something hands-on.
3. Get enough sleep, enough exercise, and enough sun/Vitamin D (in order of importance); these plus a renewed focus on incremental improvements go hand-in-hand.
4. Don't be afraid to work less. Our culture is toxic with the obsession of "what do you do" and "how much do you make" questions upon meeting someone. The most fulfilled people I know start with "what do you enjoy most" or "what's your story?" Working less makes your answer to those questions more interesting.
5. Exercise gratitude. By this, I mean find something every day you are grateful for—this forces you to think creatively and to observe the small things. It's simple, but this has larger implications for seeing the 'big picture' and seizing opportunities you may otherwise miss.
what culture is this?!