This app has 16 meditation and breathing exercises for free, including a 7-day beginner’s program. (It includes soothing nature sounds like rain and a mountain lake to help you relax in noisy places like on an airplane.) There are also free 21-day programs that focus on stress management and calming anxiety. They also vary in length, from 3 to 30 minutes.
Some of the more in-depth programs are only available by subscription ($60 per year), but cover such helpful topics as transitioning to healthy sleep, stopping stress eating, improving your relationship with yourself and more.