Numble - It's like Wordle for Math equations.
Headspace - Meditation made simple. Brilliant things happen in calm minds.
Guriddo - Guriddo (グリッド, Japanese for grid) is a free and competitive number puzzle app with daily challenges.
Calm - Calm.com can help you reduce stress and increase calm.
BioBase - Measure and manage your stress
Pacifica - Stress and anxiety relief through beautiful CBT tools