What advice would you give your twenty-year-old self, and what should they ignore?

I go back to this idea that I only discovered when I was older. I wish I had known it when I was younger, because I think I missed a lot of observations in life. That is to develop your own philosophy. I always thought philosophy was one of the most useless subjects in the world.

So given a Time Turner, I would tell my 21-year-old self that personal happiness lies in knowing that life is not a check-list of acquisition or achievement. Your qualifications, your CV, are not your life, though you will meet many people of my age and older who confuse the two. Life is difficult, and complicated, and beyond anyone’s total control, and the humility to know that will enable you to survive its vicissitudes.