If you've had your iPhone for a few years, it's time to replace the battery and give your iPhone a new lease of life. Changing the battery on an iPhone may not be the easiest, but if you follow an instructional video it will be easier. For example, search for "iphone battery replacement" on YouTube. There are many instructional videos to choose from.

Battery replacement is at your own risk. Keep in mind that opening your iPhone will void your warranty.