I'll tell you what I would tell myself if given the chance: Learn to take (calculated) risks and to be free of the weight of the judgement of others. Learn to do the baseline things that keep you healthy in body and mind and maintain them.

As for reading, I don't think any one book will affect everyone the same way or have the same impact, but do read. Don't be afraid to read things that make you uncomfortable. In fact, embrace discomfort in reading and in all aspects of life.