業精於勤，事立於豫

on the second thought 仔细想了之後，如果你想改變主意，就可以用這句話，這句話的意思是「經過第二思考後」，表示你做了新的决定。 

I was going to tell him the truth, but on the second thought, I think it's better not to.
我本來要跟他說實話的, 但是我又想了一下,還是不要的好。