What if you had a friend who was trying to lose weight, but they never stepped on a scale and didn't know their weight when they started? I'm sure, being a good friend you would suggest they find our their true weight, so they could track their changes and get a sense for if they were heading towards their goal.
Now take that same principle but apply it to your business. Whether it be sales, marketing ROI, or employee turnover, knowing where you stand is a huge part of success, and knowing if you are (or will) meet your goals. Having those metrics in hand will also help you determine the time it will or has taken you to reach your goal and provide a critical baseline for further attempts to improve your numbers.
The truth is this - if you don't keep track of your numbers, you will always think your track record is better than it actually is, because our brains can sometimes confuse intention with action. Numbers don't lie. Creating a hard goal will allow you to be objective in its achievement and is easy to measure. This number should be shared in your daily, yes daily, meeting with staff so everyone knows where you stand. Why daily? Well, if you measure the important goals quarterly, or even annually, you deprive yourself of critical moments to adjust your course which could mean the difference of a goal exceeded and one which has fallen short.