brush miles 的字面意思是“画笔里程”，put in those brush miles 的字面意思则是“增加画笔里程”，这里引申指“多画多练”。

本段大意：Paint often and paint from life. There’s no better way to improve than to put in those brush miles. Whether you paint still lives, portraits, or landscapes, paint from life as much as possible. You’ll develop that painting muscle memory that only comes with repetition. 要经常画，要写生。没有比多画多练更好的提高方式了。无论是画静物、肖像还是风景，都要尽量多写生。你要培养绘画的肌肉记忆，而这种记忆只能通过重复来实现。