Might sound daft, but it's getting up early and going to the gym for me. Everything in life spirals positively if I get that done.

I get back, I shower, eat clean because I went to the gym. Then I'm buzzing for a few hours of hard work. More often than not I'll spend my lunch break doing something constructive like reading.

Later on I'm tired because I got up early, so I go to bed earlier, and get up earlier. The cycle repeats.

I avoid all social media like the plague, with Reddit as far as I'll go when I'm being a useless idiot (like today).

Other important stuff like 'not worrying about what you can't change' has already been covered, but I like to read or listen to some Stoic philosophy every now and then (which is based on that premise to some extent).

The opposite is what I've done the last few days. Gone to bed around this time, get up late, don't get dressed. Start work without showering, skipped the gym, get a takeaway etc etc.