Lost 40lbs+ and In desperate need to get motivated to lose the remaining 10/20lbs

Without knowing your previous intake or exercise level here are some generic ideas that may help you or anyone else:

Start a fun new exercise or physical activity. Find an inspiring friend or dog who will do activities with you. Weigh your food. Try some new healthy food recipes. Drink the right amount of water. Buy an inspiration outfit. Write an inspirational letter to your heavier self. Talk to someone who is just starting out and has that vibrant excitement and see if you can borrow some of that excitement for yourself. Talk to someone who is thinking about starting to lose the weight but isn't quite there yet and tell them all the things they have questions about.

Have you reassessed your calorie goal since you lost the 40lbs?
The less we weigh the less calories we need to support our bodily functions.
Go into your goals and update them.

Tighten up your logging. We nearly all get lazy and take certain things for granted after we have been logging for a while. Be diligent in weighing and logging everything, checking that the item you have selected is the correct one- double check against packaging or the USDA.

If you are exercising- are you overestimating your calorie burn now that you are 40 lbs lighter?
Again being lighter will mean you are burning less calories doing the same workout. The difference may only be in the 10's of calories, but when you are close to goal weight you have less wiggle room in your calories and precision (as close as one can get anyway) matters.

Cheers, h.

ETA: your goal should be around .75-.5 lbs a week as you get to the last 20 lbs. It does slow to a crawl with these last pounds. The body doesn't have as much fat to draw on, and you don't want to lose more muscle than necessary, so realise it will be slow and relax.

Stay at maintenance a bit and enjoy your accomplishment, then knock out the last bit.