I am the worst hypocrite for this one, but eating decent food prepares your mind and body for all aspects of life. Junk food makes you sluggish and changes your body in a negative way, leaving you distracted from your primary goal; sometimes the sugar-rush isn't worth it. Eating well, however, does the opposite. When I'm on top of my motivation game, I use Joe Wicks' (The Body Coach) recipes to eat well. Well-being is very much a cause and effect, all-encompassing project, and it starts at home.
No, not that. Water. Your body is mostly water, so water is what it needs. Again, it's likely the healthiest drink you can have (fuelling every single part of you), rather than a caffeinated, carbonated quick-fix that will have you on a downer once the instant effects have worn off. Plus, I think the amount of time you spend waiting for a kettle is laughable.
Do something physical. I was convinced that I was extremely active at work: up and down corridors, around the classroom, etc. However, after using a step-counter for a pretty normal day, I was shocked at how few steps I had done. Sweat out your stresses with some activity. A long walk, a quick HIIT session or something more substantial can really help you in all areas. Again, I use the Body Coach to help me (and if you have ay motivational tips to help me, I'd be really grateful). You'll sleep better, making you more productive when awake (which means you'll get more done, immediately cancelling out your likely response of, "I don't have time") making more time for yourself.
If you EVER cancel plans for the sake of work, I'll be cross at you. Please note, however, that this is different to MAKING plans, when you know you have a lot to do. It's a balance. I used to do something I called Social Wednesdays, which meant that every Wednesday, after Staff Meeting, I did something with friends. I loved it, but it became expensive. The idea is the same though. Agree with yourself a slot of time when you'll be doing something you love.
My school is all about mindfulness at the moment. Our aim is to have the teachers and children practising it. Mindfulness comes in all forms, but (probably rather superficially) we all related it to relaxation. While it's supposed to be about 'living in the moment' and such when used prim and properly, there's no denying that it helps you chill out too, often sending you to sleep (a sign that your mind and body probably NEEDED to sleep). Take a moment to rest. Going from activity straight to bed, probably won't help. Stop, breathe and think of nothing.
If you've had a productive day of eating well, keeping hydrated, storming through a chunk of your undeniably increasing to-dos, a quick sweat, you're going to be delightfully smug, leading to a better sleep and an already winning tomorrow.