i'd say its subjective based on my overall interest in the subject matter im asked to focus on. i will assume it is focus on a work related task.. it helps a

i'd say its subjective based on my overall interest in the subject matter im asked to focus on. i will assume it is focus on a work related task.. it helps a lot to find your happy place; rest (sleep and time away from said thing-to-focus-on) does wonders. its all too easy to go over the limit and keep working on a task trying to "bang it out" - take care of yourself first before you can take care of anything else. background music, or background silence does wonders for me; but everybody will be different. try to take some mental notes on what derails you from a task - if its just "tired" then take a break (context switch to something else) - if its "stuck on problem" - walk away and casually think about it (or try to think of other paths to solving a task)