"If you let go a little, you'll get a little bit of peace. If you let go a lot, you'll get a lot of peace." -- Ajahn Chah
Your mind is in many ways similar to a body of water. Just as throwing rocks into a pond or navigating a boat through a lake will create ripples and waves, being constantly exposed to stressful interactions and over-stimulation can agitate your mind and leave you feeling stressed out, irritated, and emotionally drained.
When you experience stress and anxiety, it's important to remember that your mind, like water, will become calmer if you shift your awareness away from the things that are creating the ripples. Traditionally, this is done by anchoring your mind to an object in meditation for lengthened periods of time. The object can be anything at all -- you can focus on a beautiful statue or painting, contemplate a flower or other natural object, or focus on something internal like the sound of your breath or a mantra to redirect your awareness away from potential stressors.
Once you've chosen your object, the practice is simple: Focus your eyes or your awareness on your chosen object and redirect your focus back to it every time you check out or mentally wander elsewhere. As your thoughts arise, don't try to stop them. Instead, just allow them to come and go like waves settling back into water.
At first, you may find that your mind wanders quite a lot. After a while though, you will find that it becomes easier to remain anchored to your object as the waves in your mind start to settle and your thoughts begin to slow. Stick with it, continue to let the waves settle back into the waters, and at some point you may even observe the stormy ocean of your thoughts transforming into a placid sea of peaceful awareness.
Practice this short meditation twice daily for best effect.