but to the general question - ultimately because if you don't care about yourself, nobody else would. Just take it one step at a time. If you want to tackle sleep - always a good idea and a good start - tackle sleep. Do not try to take on too much at one time, because you'd be setting yourself up for failure.

Success DOES breed success, believe me, but you need to make your task small and doable so that you can achieve success and build upon it.

Also, your goals are interdependent. You listed (I am paraphrasing and switching order a bit):

1) getting enough sleep
2)not watching TV or surfing the web all day long
3) movement
4) good food

If you get enough sleep, you will be more likely to feel cheerful enough to go for a walk.

If you go for a walk, you will be more likely to have restful sleep.

If you go for a walk, that would be time not spent in front of a screen.

If you spend less time in front of a screen, you will be more likely to have restful sleep.

To eat good food, you most likely will need to cook some, which also will be time not spent in front of a screen.

And so on.