Learning Sanskrit. I have spent the last few years learning it and it's been tremendously rewarding. Sanskrit is a beautiful language. Learning it is a great mental challenge and gives great satisfaction (to me). Before learning Sanskrit I had never really pursued a hobby this seriously. Since I have been doing this I no longer feel like a machine who just goes to work, eats and sleeps. Before this, I used to feel great despair if the work in the office was not to my satisfaction. Since I have started pursuing this passion, work no longer dictates my life. Work is not the only thing that makes my life meaningful. I view work as one of the important things in life and not the only important thing in life. And that has made all the difference. My contentment and happiness level has gone up dramatically since I have been learning Sanskrit.