In the growth mindset, it’s almost inconceivable to want something badly, to think you have a chance to achieve it, and then do nothing about it. When it happens, the I could have been is heartbreaking, not comforting.

There were few American women in the 1930s through 1950s who were more successful than Clare Boothe Luce. She was a famous author and playwright, she was elected to Congress twice, and she was ambassador to Italy. “I don’t really understand the word ‘success,’ ” she has said. “I know people use it about me, but I don’t understand it.” Her public life and private tragedies kept her from getting back to her greatest love: writing for the theater. She’d had great success with plays like The Women, but it just wouldn’t do for a political figure to keep penning tart, sexy comedies.

For her, politics did not provide the personal creative effort she valued most, and looking back she couldn’t forgive herself for not pursuing her passion for theater. “I often thought,” she said, “that if I were to write an autobiography, my title would be The Autobiography of a Failure.”

Billie Jean King says it’s all about what you want to look back and say. I agree with her. You can look back and say, “I could have been. "Polishing your unused endowments like trophies. Or you can look back and say, “I gave my all for the things I valued.” Think about what you want to look back and say. Then choose your mindset.