I did some quick looking and found a free video for you. There are many different kinds of yoga. You need to practice hatha yoga which involves the purification of the body as a gateway for mental purification through extended meditation. I know it sounds like a bunch of hippie jibberish. The important thing to remember is to always be aware of your body and keep your mind clear. You can't allow any thoughts to enter your mind other than what you're doing. You must concentrate on your breathing, taking the deepest breaths you can. After some practice, you will be able to meditate without forcing thoughts of everyday things out of your head, you will become more aware of your body and will improve your mental clarity.
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Imagry is important to get the desired results. When you sit, ground your sit bones and imagine that there is a string attached to the top of your head, pulling you up to the sky. Everything you do must be balanced and equal. What you do on one side, must be done on the other. When you breathe, imagine that your lungs are an umbrella. When you inhale, imagine that you are slowly opening that umbrella and when you exhale, you are slowly closing that umbrella. Concentrate on your breathing and your body will follow. It's useful to play relaxing music when you begin. I find that it's easier to block out things when it's not silent.
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