I walk at least 4 miles a day. Looking back at my daily mood, diet, and health data, it seems missing a day can have negative knock on effects that can last a day or two, and longer if I miss several days. I sleep deeper, eat better, feel less stress and generally happier. I also get a lot of my work done in my head (software, of course), more so if I leave the earphones at home. Even the treadmill helps notability, although I think sunlight and the peace of outdoors is more effective. I don’t have the same data but my estimation is that strength training didn’t quite have the same effect other than physical health (for me). Now, if only I could get myself to do both… I don’t enjoy strength training and it’s been hard to keep doing it consistently.