Lots of different ways.
Wearing a watch that beeps every hour so I know how much time has passed, using a day timer agenda type schedule book to keep track of things I need/want to get done, making healthier habits some of my special interests so I don't have to force myself to spend time on them, rewarding myself with time to do what I really enjoy after getting some stuff done that I don't want to do, and having a "why," or two or three when it comes to bigger goals I want to achieve. Having a reason bigger than myself to accomplish something helps keep me on track with working towards it & avoiding sinking too too much time into a special interest that doesn't serve me in accomplishing what I want to.
I'm not aways successful with everything, as I do still tend to waste too much time online especially, but whatever - I'm a work in progress & always will be. As long as I keep moving forward and getting better at the things I need to and want to, it's all good.