Whenever someone says they are going to give 110%, I have to laugh. Not only is it mathematically meaningless, but the people who drag out this well-worn phrase are typically those that give a half-assed effort on most days. What they are really saying is that they are going to bump up their typical 60% effort to a strenuous 75%. Don't tell me how hard you are going to work, just show me.
It is like when someone would tell me they were a great tipper back in my restaurant days. My response (in my head) was "no you're not", but they received the same level of service as everyone else in my section. I am not sure if they were just trying to get the monkey to dance for the promise of a shiny object, but they were never "great" tippers, and were often quite cheap.
If you feel the need to boast before you bother to make the effort, you likely have nothing to boast about.