It is not an English expression as you write it - one has to keep one's own head up, not someone else's 不要灰心,别灰心 We say 'keep your head up - that mean's 'Don't be discouraged' ' - or hold your head high = be proud

我会让你昂首阔步

我会做你坚强的后盾or我会让你一直抬头挺胸／昂首阔步

Where did you see this? Is it quoted correctly? Was it from a native speaker of English? Probably not.