Here's a letter I would have written to myself back when I was 25.
Don't spend your energy worrying about things ... everything always turns out all right. Pay attention to your gut; it's rarely wrong. Don't be upset or depressed when things are not perfect; life is a combination of good, bad, happy and sad days and experiences. Don't be afraid to have an opinion or disagree with someone who has a different point of view; your voice counts. Don't give up your values or principles for a man; the right man will love you just the way you are. Don't lose yourself; laugh as loud as you want and be every bit of yourself as you are. Don't sell yourself short; you won't always be the smartest, but you will work harder than anyone else. Don't spend what you don't have; you will always have what you need. Don't give up on love; you will find it much later in life and it will be worth the wait.
Be present everyday and savor every moment, whether it is joyful or painful; there is a lesson in everything. Everything happens for a reason.
Be kind, be generous, be grateful, be content, be happy. You'll be just fine.
You know that fear that you have about producing ugly children? No worries, they all turn out to be gorgeous!