0 (of a part of the body) to be reduced in size and therefore strength, or, more generally, to become weaker -- (身体部位)萎缩;衰退
We can complete it step by step however long the road is and it can't be completed however short the road is if you don't even mark your footprint.
再长的路,一步步也能走完,再短的路,不迈开双脚也无法到达。