You could add reading the forum to that list 
busy threads like the daily check in, meme wars in particular. I like the mental health memes and pet threads too.
Meditation has been mentioned a few times, it was huge for me when I stopped drinking. There are loads of threads on here with good app recommendations if you use the search bar 
but here is one with some YouTube links
I have fallen out of regular meditation practice but I keep coming back to it. One day I will get through this 40 day Tara Brach course
https://courses.tarabrach.com/courses/mindfulness-daily
Yoga is another good way of developing mindfulness, a few of us are doing Yoga With Adriene’s 30 day journey at the moment
https://talkingsober.com/t/move-yoga-challenge-ywa/132857?u=siand
You also mentioned walking - there’s a thread for that too 