I've been pretty fortunate, but there have been a few key moments that I really look at as transformative and incredibly lucky.
1. I took a random interview to be someone's assistant (not even thinking I wanted to job, but eh, might as well take the interview). The guy I was interviewing with turned out to be the founder of a small web development studio, and after talking with him at great length, he decided to offer me a job, but not the one I'd applied for. Instead of being his assistant, I'd be a Project Manager and oversee the development of the social network he and his team were crafting.
I'd never done anything like that, but I figured it could be fun, so I said yes. Three years later, it's taken me down an amazing path working in development. I've had a hand in creating websites, released a video game and amassed tons of awesome, really useful skills. All because of getting an awesome break.
2. Moving to Chicago. Good lord was I ready to leave South Florida, and ever since I've moved to my new city, I've never been better. Even on bad days, I'm so much happier than I was in Florida.
3. Oddly enough, just last night around 2 AM I had a mini-epiphany that I'm just really happy with my life right now. I'm doing cool stuff professionally, I have a great group of friends (I was walking home after a great Taco Night on of my buddies hosted) and I'm even seeing a really cool girl at the moment. Looking up into the night sky during the stroll home, I just felt really content.