Meditation is a technique of achieving peace of mind. It works by concentrating your attention for just a little while on the here-and-now. Just 15 or 20 minutes a day are all that is needed.
There are many kinds of meditation. This will teach you one simple technique, which is similar to Transcendental Meditation. Transcendental Meditation, or TM, is different because a practitioner supposedly analyzes you and determines a prescription of a "mantra," or a word you say or think when you meditate. This is a foreign (Hindi) word you don't know the meaning of, and in my view, could not have a special effect on you if you do not understand it.
Herbert Benson, M.D., has written a book, The Relaxation Response, in which he says it does not make a difference what word you use, and he suggests you just say or think "one." I use the sound "shahm," because I read it in a book once.
This is done by sitting down and making yourself comfortable, to begin with. Do not lie down, because you will likely fall asleep if you do that. Close your eyes, and repeat a mantra, either mentally or aloud. Do this for 15 or 20 minutes a day.
Do not use a timer, because it tends to jolt you when it goes off. Instead, just take a peek at a clock from time to time. Don't worry if your mind drifts. When you notice this, just return to what you were doing, and continue.
Afterward, wait at least an hour before you engage in exercise, such as running. Meditation actually causes the metabolism of your body (conversion of fuel to energy) to slow down.
Over time, notice if the amount of time you spend worrying, or feeling anxious, or feeling resentful or angry, or another negative feeling has reduced. Notice your sleep patterns and appetite patterns, to observe whether there has been a change. Work it into your way of life, and just make it a habit.