Hello comrades and welcome to the first improvement megathread of December! 
How was your November?
Do you have any goals for December?
Poster caption: Chairman Mao gives us a happy life
Mao zhuxi gei womende xingfu shenghuo
毛主席给我们的幸福生活
Good luck with your goals! 
Hell yeah walking is the one of fundamental self improvement things that I think gets gravely overlooked. Moving those legs and getting some fresh air is critical to creating a better self great job!
Been touching grass a lot more lately too, big recommendation too.
The cardio and leg exercise is obviously good, but I feel like a nice walk is even better for my mental health. Just setting aside some dedicated time to unwind walking and clear your head pays dividends for dealing with stress and helps me be more mindful and focused in the other things in my life. I'm bad at just sitting and meditating, but I'm pretty good at putting one foot in front of the other over and over.
(Flexibility work/stretching routine is good for that too. I'm surprisingly limber now considering my size and build, I can plant my palms in the ground straight legged touching my toes for the first time in more than a decade.
)