I don't manage them. Managing tasks doesn't change the likelihood of them being done; it only changes the order in which they'll get done, if they get done at all. Changing the way you plan won't magically motivate you to do stuff.
The way I get tasks done is by doing them immediately I see that they need doing. If you can develop that habit then tasks won't even need managing, you won't need to set time aside to do things, and you'll always be on top of things. Sometimes it's really hard work to keep at it but your future self will thank you.