This is a great question! Sometimes for me it seems so easy to find motivation. At other times it is a S-T-R-U-G-G-L-E! But I know that's not helping so far. Lol. I'm just giving you some context.
At the end of the day, I have a few things that motivate me ... when I need it.
I look to incredible things that other human beings have done, and just remember them. Then dwelling on their moment of accomplishment, I push on.
In a larger sense I look towards goals (which I try to break down - sometimes not too well - into bite size actionable chunks). This helps, but it's not flawless. I find that the biggest obstacle for me is feeling overwhelmed. Hence, why it's so important to break my goals into action sized chunks.
I earnestly hope this helps you out.