It is a waste of time (and expensive art materials,) in trying to force yourself to paint when you are not in the mood.
Here's a few personal tips on getting oneself motivated and finding the time to do some art:
1. Have a source of income other than art, so that you can paint when you feel like it - not just when you need money for food, rent and beer!
2. Have a bit of space, (a spare room, well-lit garage - or even just a corner of the living room if you are not lucky enough to have your own studio,) where you can leave all of your gear out. That way, when the mood strikes, you will not have the bother of getting all your art materials and accoutrements out before you can even start. This is a great way of maximizing your precious painting time...
3. Unplug the computer!
4. Unplug the TV
5. Put on some nice music.
6. Take the dogs for a walk first. Get them tired-out - and then you can concentrate on your art!
7. Open a can of cold beer or a bottle of nice red wine.
8. Get some painting done before you fall asleep!