When forming a habit, a ‘no excuses’ approach might be the most effective.
Because as soon as you give yourself an excuse, you pave the way for bigger excuses the next time around.
“I won’t go for a run today, because I slept late” becomes, over time, “I won’t run, because I’m lazy”.
As soon as we give an excuse to miss the mark 1% of the time, we soften our “excuse threshold”.
Sometimes, it’s better to stick to 100% when we want to form a habit.
(I read a variant on this advice somewhere else, that was better expressed. Will look for it.)