Wish I did it at 19!
At age 19 in the mid-80's, I could've moved from St. Louis to Champaign-Urbana, ILL with my fellow compu-geek buddy and gotten a programming job with a little known company called Bruce Artwick Org, who made this quirky little program called Flight Sim, which was later sold to Microsoft. I instead opted to serve my country like the previous generations of my family and entered Uncle Sam's NAVY and learned how to operate a submarine nuclear plant.
I could be a retired Microsoft millionaire like my buddy is now, but as I look back on the last 20 years, the life experience I accumulated in the Navy, nuclear utilities, and working with some wild stuff at the Los Alamos National Laboratory, I have no regrets chucking it all for the job I now hold flying the CRJ. Now, I wouldn't mind having a fatter bank account, but I'm rich in life experience, family/friend ties, and in my faith.
Had I done it at 19, I may be holding a major CA seat right now instead of regional FO, but that 'book' would, in my opinion, be a little less of a good read!
Follow your dreams, or you'll always be looking back or up and wondering 'what if...' I just had to give my childhood dream a shot or it would've haunted me for the rest of my life.