Always leave some rooms for improvement

I have never put in more than 70% effort in whatever things I do. Why?

Because...

1. I'm lazy in nature
   
2. I'm highly efficient, my 70% effort is equivalent to 100% effort of most people
   
3. If I put in 70% effort in something, and the return is below my expectation, I'd count myself lucky that I didn't put in 100% and waste my effort; on the contrary, if the return is beyond my expectation, I gained.
   
4. I would always reserve some resources and leave some rooms for improvement.
   
5. Did you watch horse racing before? The first horse that dashes out and leads initially will never win the race.