Dear 20-year-old Tiffany...
Hello young lady. You have a lot of learning to do. But in the meantime here are some things that might make the trip through these roads a little easier.
First of all, don't worry so much about whether you're going to get married young or not. You will get married young to a wonderful man, but the thing is that you will have many friends that will get married much much later, and it will never seem as though they are too old to be "tying the knot." Getting married out of college or not at all should be the least of your concerns. And besides, that's a lame thing to worry about when you're so young.
Secondly, you've just started dating this guy that totally cracks you up. I know you're totally obsessed with him right now, but there will be times when he might drive you crazy, or your feelings for him might drive you crazy. Take a step back and be nice to him. He will always be good to you, so always be good to him.
Thirdly, ask for help. There is no reason to be the martyr and no one ever remembers your martyrdom nearly as well as you do. Therefore, it is pretty much worthless. It is ridiculous for you to do it all by yourself when you are surrounded by people that want to help you.
Fourthly, those friends you have right now that "adults" keep saying you will lose touch with? They're wrong. The friends you have now are going to be great friends for a long long time, so don't stress about the changes that are ahead. Things like distance, volunteer service, marriage, and children are not going to change how cool you all are and how you fit into each other's lives perfectly everytime you are together.
Fifthly, you don't have to move somewhere drop-dead exciting right out of college in order to really live. You don't need a big city to make your life shine. You are perfectly capable of making the place you move to - no matter how ordinary - shine on its own.
Also, success comes in many different forms. Recognize those forms and don't get sucked into the art world's, and society's, definitions of success.
And lastly - be open to ideas, people, places. You are never too good for anything or anyone. Open up your life to new things because those things are what will make your life beautiful.
Appreciate your family and friends. Life is too short to put things off. Lives will be cut short and people will leave. Love them with everything you've got in the meantime.
And p.s. you will have an awesome family.
Sincerely, your 30-year-old self.
**Explanation: I heard a report on NPR last night about a woman blogger named Cassie Boorn who has asked other bloggers in their 30s and 40s to write letters to their 20-year-old selves. She has collected so many letters and uses them as valuable advice for herself as a 22-year-old single mother. Read more about the report here and I invite my fellow bloggers to write a letter to their younger selves. It is fun. :)