There are a lot of different reasons why yoga is beneficial, but the main reason I believe, is to connect with yourself and the world around us. Connecting the dots and seeing the patterns that appears. The realization that everything is connected, and feeling the oneness. The word "yoga" means "union" in Sanskrit, and to me that is pretty self explanatory.
Having yoga as a part of your daily routine is an investment in yourself, not only for the longevity of your life, but also what you accomplish during it. Yoga allows you to better understand yourself, strengthen your weaknesses and finding your place in this world.
We feel pretty useless if we don't know who we are and what part we play, and here I believe yoga can be the most effective tool.
Something I want to prepare you for, dear reader, is that the suffering does not end. Most of your suffering is self inflicted, so when you become aware of your self pity, you can end that suffering right then and their. But life isn't easy, and I don't know why we expect it to be. Yoga hands you tools to deal with the things that you find difficult, and much much more.