Lots of focus on the step count while IMT/IMST breathing muscle training seems much more convincing (for the young and healthy as well as for the frail):
The IMT study this is based on is tiny compared to the meta-analysis for steps. It also only tested blood pressure and for a short amount of time compared to all-cause mortality over years in the meta-analysis.
"5-minute breathing exercise lowers blood pressure better than working out, medication" https://news.ycombinator.com/item?id=27747943
"Thanks HN: For Me, Breathing exercise for High Blood Pressure is Working" https://news.ycombinator.com/item?id=27980060