What is one of the best or most worthwhile investments you have ever made — of money, time, or energy?

In the last 24 years that I have played for India I have made new friends, and before that I have had friends from my childhood. They have all had a terrific contribution. As and when I have called them to come and bowl to me at the nets, they have left their work aside to come and help me. Be it joining me on holidays and having discussions with me on cricket, or how I was a little stressed and wanting to find a solution so I can perform better. All those moments my friends were with me. Even for when I was injured, I would wake up in the morning because I couldn't sleep and thought that my career was over because of injuries, that is when my friends have woken up at 3 o'clock in the morning to drive with me and make me believe that my career was not over. Life would be incomplete without all those friends.

Of all the gifts that tennis has given me over the years, the greatest, without a doubt, has been the people I've met along the way: my friends, my competitors, and most of all the fans who give the sport its life.