13. Study abroad.
Though I did some travelling when I was younger, I didn't study abroad and it is the one thing I regret from my college years. I graduated a semester early, so I had the opportunity, I just didn't do it. I was always afraid to do things completely on my own.
Step out from your comfort zone. Don't be afraid to travel by yourself and meet new people. Often, the things we are most afraid of turn out to be the most exciting and rewarding. Discover the world. Experience other cultures. Do it before you have a full time job and a family and responsibilities that make it more difficult. Take in the architecture, the food, the language, the land. Meet the people. Appreciate the blessings you already have in your life at home. Learn from others how you can live a better, fuller life. Take lots of photographs of the places you travel to. You won't regret it.