Mindfulness is not a value in itself, but it is a core skill

I advocate three core skills:

Rationality and compassion, supported by mindfulness.

I recommend basic mindfulness meditation - sitting, breathing, focusing on the breath - as the best tool I ever learned to develop mindfulness.

For those who are interested, I suggest to learn basic "tantric" exercises - breathing, pelvic floor training, letting go of orgasm as the primary goal of sexual activity.

If you really want to, I suggest to experiment with some form of chastity/nofap/semen retention, and visualisation. In my experience, they make life easier and more fun.

I suspect that every exercise that incorporates mindful breathing and gets you more "into the body" will be a good supporting practice: yoga, qi gong, tai chi, etc.