I find that tasks expand and contract to the time that I allow them.
For instance, small things like answering email can expand to be an hour, if I give them that much time. If I give myself five minutes, then it will take five minutes.
So this is a simple, helpful reminder to time yourself.
This is what Austin Kleon recommends:
This is always my advice for people who are struggling: just sit down in front of your work every day, set a timer, and don’t get up or check the internet until the timer goes off. Something will happen.
For creative work, you want to allow yourself lots of time. Famously, John Cleese recommends 90 minutes (30 minutes for allowing yourself to settle down, 60 minutes for actually producing something). 90 minutes is good, but so is three hours. After the timer goes off, force yourself to take a break. What often happens is that you want to keep going, which is great. You take a break for a few minutes, and then come back refreshed and ready to go. This is very akin to Hemingway’s recommendation: “The best way is always to stop when you are going good and when you know what will happen next.”
I’m pretty terrible at time management and predicting how long it will take for me to do something. So this is a good solution: I tell myself how long it’s going to take, before I even do it. This lets me focus a lot better.