Some easy tricks I found to keep your motivation and keep on progressing are as follows:

Exercises, your mitochondria apparently produces happiness hormones as it creates energy for your body to use up when you move your body, but when you don’t move your body, mitochondria slows down the production of energy as they are not required as much, thus they produce smaller amount of happiness hormones, making us feel less motivated as a result.

Job crafting, it’s not always great to take things too seriously, so why not make it a little enjoyable! For example, think of it like a game. What gets you more points? Job crafting is seeing your work in a different light.

Service, when you feel like your work has a positive effect on others, you feel the sense of purpose and pride towards your work.

Imagining, when you imagine of yourself working hard towards your goal, apparently it makes you less anxious to do the actual tasks. You prepare yourself mentally for the thing you’ll be doing. (Unlike imagining yourself succeeding in the task, which makes you feel like you have achieved it. You get satisfied with it even before starting anything, achieving nothing.)

And to help with concentrating on the tiring work or research:

Meditation, well, meditating. Clears my mind and helps concentrate.

Tea, caffeine with theanine, which are both in your cuppa, is said to increase your concentration by 11% (which is a lot if you think about it)

I’ll be keep on adding to this list as I find more easy but useful tricks.