When you compare your goal with where you are now it seem far-off and that can discourage you. Start with what you have, and you’ll be motivated.
When you start at the beginning, checking progress can inspire you to carry on towards where you want to be or what you want to achieve. Doing it this way is generally motivating.
However, people often start in the wrong place, which has the opposite effect. They constantly measure negative progress by fixating about where they want to be, and comparing it with where they are now. They become demoralised by the distance between the two.
Beware compare, because it can be a demoralising distraction.