Microwaving is the only way to heat your therapy pack, but it is super simple. Just put your pack in the microwave and heat for 30-45 seconds. If it cools off, you can reheat it as many times as you want!
To get that awesome cold therapy, put your therapy pack in the freezer for an hour. For extra iciness, you can leave it in the freezer for longer, just be careful not to apply the cold pack for more than 20 minutes at a time.