Answer:
Motivation is not something that someone can tell you; motivation comes from within yourself.
It's hardest to be motivated when you haven't had enough sleep. There is no artificial stimulant that will replace natural sleep for this purpose.
The hardest things to get motivated about are things that you find boring but are required to do; things that you've done so often that they provide no stimulation; things that loom large over your head that you fear failure; and things that seem too huge to accomplish, especially with a deadline.
In all of these cases, focusing on the end result rather than what it will take to get there is the place to start. The next step is to 'lift a finger'; make any small move at starting without thinking about the whole thing. Whenever you find yourself thinking about what will hang you up, snap your mind right back to the end result and keep moving forward. For large looming or large overwhelming things, focus only on each small step and just try to accomplish that. Whenever you find yourself thinking about what will hang you up, snap your mind right back to the end result and keep moving forward. Somewhere along this process, when you can see some result taking shape, the motivation will start to grow. The large tasks ones will get done by accomplishing each smaller part; the small tedious ones may be done even before you feel motivated, but they will be done.
If you are simply unmotivated in general with nothing special to accomplish, then find a goal, even a really small one. Make a sandwich, take out the trash, then build on that step by step. While you are doing a few little things, you may be stimulated by something that will motivate you; something you had forgotten about or something new that comes to mind. It is much less likely to happen if you just sit around and wait.