help with a bridge thought

C scheduling
T I don’t know how much time a certain task will take
F stress, confusion
A do task, but let myself be interrupted and distracted
R still don’t know how much time task will take

intentional model
T The task will take as much time as I plan for
F determined
A schedule time, focus, do it
R It’s done in the planned amount of time.

So I like my intentional model, but I don’t really believe the thought yet. Suggestions for bridge thoughts?