Everyone should read this book! It had a huge impact on me and the way I choose to live my life. It will make you think about people in your life, maybe some that you haven't talked to in years! Even mentors from early in you career will be glad to hear you say "Thank You" for things they taught you.
It's easy to say "I love you" but may be a little harder to ask for forgiveness or offer it. Don't wait to tell the people in your life what they mean to you.