Mental exercises such as meditation, imagery, progressive muscle relaxation, and self-hypnosis can be enhanced with the use of biofeedback. Biofeedback uses equipment such as sensors and monitors to record physiological processes such as heart rate, blood pressure, and breathing rate in real time. This information is important. Your heart rate, blood pressure, and breathing rate are markers of your arousal level. One of the goals of mental exercises is to lower your arousal level to become more calm and relaxed. Having constant feedback while meditating can be very helpful. For example, you may think you are relaxed, but the monitor may say that your heart rate or breathing rate is high. This feedback tells you that you can relax even more. Once you see your heart rate or breathing rate decrease on the monitor, this helps you feel what it's like to be in a true meditative state. You will have a better understanding of what it means to be relaxed and how to get there. It is also motivating seeing yourself making objectively measurable progress. For these reasons, it is well worth it to invest in biofeedback equipment. There are relatively cheap handheld sensors that you can buy, and there are very advanced sets of equipment that offer many types of useful and accurate measurements on the market as well. Biofeedback is yet another way that you can improve as an athlete and gain an edge on your competition.