Meditate
Fist get comfy, you can do one of those position-a-majigers if ya want. Then relax your face, hands, feet and anything else you can. When you're sure you've done this, start counting your breaths. Count from one to ten and then restart, don't try to control your breathing and don't think of anything else, if you find yourself distracted then restart your current count. When you finish (I set a timer for 45 minutes) get up and stretch. You may have noticed the first time, maybe the second time, and for some the fiftieth time that a lot more thoughts go through your head than you think. You should get pretty good at concentrating on one thought and blocking unnecessary distractions.