Does meditation really help us?Is it useful?

Well i have been reading about yoga and meditation and how it relaxes your body, helps you calm down and concentrate. Well I am a willing learner, and try out yoga postures daily. It does help me relax and increases y flexibility. However I have my doubts about meditation, the real dillema for me is that if I want to learn to concentrate i can't help but ask how is sitting there doing nothing helping? My type of meditation is just relaxing and concentrating on breathing. This should be done for around 30 mintues or so. That is where my problem lies, i can't get myself to do it when i know so much can be done in half an hour instead of just sitting. If someone can convince me( and i really want to be convinced) I can sit down with a good conscience. Any personal experience or types of meditation would be appreciated as well . Please NO LINKS TO WEBSITES!