If I can only pick one app to use for my mindfulness practices, I would undoubtedly choose Headspace. Headspace includes an extensive library of guided meditation that can help you through the day. The instructions are easy to follow as a beginner, and the app provides a wide range of contents that can help you destress, stay focused, and sleep better. As you get more experienced with meditation, they also offer courses that span multiple days on topics such as finding acceptance, gaining clarity in mind, etc. Plus, the animations in the app are so cheerful, friendly, and encouraging!