Focusing on breathing without thinking about anything else - isn't easy. Jon Kabat-Zinn recommends practicing mindfulness meditation 45 minutes a day but suggests starting out trying this exercise for just a few minutes:
1. Assume a comfortable posture, lying on your back or sitting (if sitting, keep your spine straight and let your shoulders drop).2. Bring your attention to your belly, feeling it expand gently on the inbreath and fall on the outbreath.
3. Keep your focus on your breathing, for the duration of each inbreath and outbreath, "as if you were riding the waves of your own breathing," says Kabat-Zinn in his book "Full Catastrophe Living."
4. Every time you notice that your mind has wandered off the breath, notice what it was that took you away, then gently bring your attention back to your belly and your breathing.
5. Practice this exercise at a convenient time every day, whether you feel like it or not. Be aware of how it feels to spend some time each day just being with your breath without having to do anything.