Hey @kyle-goetz , klar, lass mich mal erklären!
Mühsam ernährt sich das Eichhörnchenis one of my favourite sayings! It basically means little by little or slowly but surely . Interesting that you haven't heard of Little by little, the bird builds its nest. If the former is easier to understand, I am happy to change it.
I would use this idiom if I feel like I have to take baby steps to achieve a task / goal. For example:
Es dauert ewig eine Sprachlernapp zu bauen... aber, wie man so schön sagt, mühsam ernährt sich das Eichhörnchen.
Or you might watch your daughter taking her first steps and learning how to walk, continually fallings down and getting back up, and comment to your wife "Mühsam ernährt sich das Eichhörnchen" . Get my drift?