I just finished reading Barbara Brown Taylor's An Altar in the World, and in her chapter "The Practice of Saying No: Sabbath," she includes an exercise that I've adapted a little and am going to try. I invite you to try it, too.
First, get a pencil and a piece of paper and find a few minutes that you can be alone. Then, on one side of the paper, list "all the things you know give you life that you never take time to do." What makes life meaningful to you? What's the life like that you live in your innermost dreams? What do you do in the life you meant to live but haven't gotten around to yet? Think about standing at the end of your life looking back over it: what would you wish you had included? changed? left out? Do not judge yourself or edit your list. "Promise not to shush your heart when it howls for the list it wants," Taylor encourages.
Now, flip the paper over and "make a list of all the reasons why you think it is impossible for you to do [or be] those things." That's all.
But now a seed has been planted. Maybe your longing heart will find a way through all those excuses. I hope mine does.