Think of the reasons why you wanted to clean. Stuff like – there's no point in keeping all this junk if I haven't used it for a long time and its just taking up space.
For me, because I was donating my stuff, I thought about how other people may want and need those things more than I do and that I'd rather it be reused to make someone happy, than sit in the corner of my room.
So once again, you can't just get motivated because being lazy and procrastinating is easier. Let's be real. But honestly, you don't even need motivation, you just need to get started. Because sometimes even after you read this, you still won't feel motivated. So start small or just go full out, whatever works for you. You gotta JUST DO IT!