"Really build up" is a common phrase that implies the act of enhancing or strengthening something. If you're looking for synonyms for this phrase, there are a plethora of options to choose from. Some alternative ways to express this sentiment could be to intensify, amplify, boost, augment, or reinforce. You could also use words like fortify, enhance, elevate, improve, or grow. All of these words paint a clear picture of the idea of improving or growing something, whether that's physical strength, mental prowess, or even just a good story. Whichever word you choose, it's clear that the act of building up is essential to progress and success in many areas of life.