however strong you are, there is always someone stronger (idiom) / there is always sth more to learn / never be satisfied to rest on your laurels / there is no room for complacency
lit. When we get to the mountain, there'll be a way through. (idiom) / fig. Everything will turn out for the best. / Let's worry about it when it happens. / It will be all right on the night. / cf couplet 車到山前必有路,船到橋頭自然直|车到山前必有路,船到桥头自然直