Well lately there seems to be none at all. My boring 'go nowhere' job is swamping me with a bummed-out feeling. Not to mention taking on the responsibility of taking care of my Mom who had a stroke a couple weeks ago...........
I need a hike in the park or maybe a couple days off already. Probably should be doing that instead of reformatting a laptop for a few bucks; but, I desperately need the money.
Keep smiling - then sooner or later

I'll be drawing again.
Everyone is different when it comes to motivation though. If you know why your not motivated - it helps to over come it.
Simple suggestions:
Hike
Exercise
Get away for a breath of air outside the studio
Go to dinner at a really good restaurant
Spread gravy down the front of your new white shirt
A can of silly string is good...
Know thy self - the main key