What is the thing you want to absolutely achieve? Tomorrow, this week, this month, this year.
What is it that you need to do to make it happen? Make a list.
Go through the list, one point at a time, and do not shift your focus until the list is done. Do rest, relax, take breaks. Particularly if the list is long. But do not invest energy, time, and meaningful work on a new shiny object.
Once you are done, reassess and celebrate the work you have done.