Fascinating. Your description of the essence of inner healing - Learn to sit with and accept all emotions, as well as taking action when possible - is beautiful.

I would add one foundational thing to your description, and add a qualification to your recommendation to use "hacks" sparingly.

As we can see from the explosion of the "third" way of mindfulness - from Zindel Segal's Mindfulness Based Cognitive Therapy for Depression, to Dan Siegel's profound work on awareness and brain/body/interpersonal integration, to Steven Hayes' ACT, and beyond that to Loch Kelly's non dual "Effortless Mindfulness" approach - if we attempt to sit and face all emotions from within the very cramped, limited identity we normally take to be our "self," we may bring about some temporary change but it is not likely to be truly transformative.

As far as brief interventions such as breathing, relaxation, mindfulness breaks - I would say, rather than doing them as a bandaid to "fix" stress or anxiety, if you build pauses (exercise snacks as some call them, or mindfulness snacks if you like) into your day, this has been shown to have powerful long lasting effects if you truly love them.

For example, it's about 9:20 AM and I'm taking a break from some grueling mental work figuring out some difficult software. I know in the morning, I tend to be hyped up when working, so the Qigong form, 8 Brocades, is a perfect break. You can do each one once, in which case it takes barely more than a minute, or you can do them as many times as you like: https://www.youtube.com/watch?v=cwlvTcWR3Gs&t=871s This video is 20 minutes, and I STRONGLY recommend you memorize it so you don't have to go to Youtube and get distracted by animal videos or 90 year olds dancing or Keanu Reeves answering the phone or whatever.

In the afternoon, I tend to be a bit more fatigued, so something more aerobic can be helpful. And all of it can incorporate breathing, relaxation and mindfulness: https://www.youtube.com/watch?v=xLlE7csP1KI&feature=youtu.be