Alternate Nostril Breathing (ANB)
Routine: 2 minutes ANB. Rest* 1 minute. 2 minutes ANB.
Benefits: Good for when you're feeling overwhelmed by tech or too many thoughts at Video example: https://www.youtube.com/watch?v=8VwufJrUhic (3:20 - 4:56)
Notes: A lot of the videos I've found online have an awkward hand posture. I'm not sure it's necessary. The general idea is to close one nostril at a time and alternate breathing.
Bhastrika / Bellows breathing (BB)
Benefits: Good for energy.
Routine: 3 sets of 20 BB. Rest* 30 seconds between sets.
Video example: https://www.youtube.com/watch?v=DByVSR2fX0k&t=1s.
Notes: It might look a little funny, but it's worth a try. If you can, I would recommend sitting in vajrasana (https://en.wikipedia.org/wiki/Vajrasana_(yoga)). No worries if you can't sit like that.
Rest means sit with your eyes closed and breathe normally. Rest your hands on your lap palm facing up.
Ujayyi Breathing (UJ)
Benefits: Really nice and really subtle breathe you can do anywhere. This is actually a very useful breath to be aware of.
Routine: 2 minutes UJ. Rest* 1 minute. 2 minutes UJ.
Video example: https://www.youtube.com/watch?v=ZwEdfOuhoY4
Notes: Foundational breath for yoga and pranayama (pranayama means breath control)
I personally do pranayama (3-stage pranayama w/ UJ breathing) with bhastrika and a kriya breathing exercise (SKY breathing) every morning. I also occasionally do alternate nostril breathing before meditation. This is something simpler, though, that I think anyone can try out and see if it works for them or not. There are also a lot of other good comments in this thread, but this is what I have personal experience with.