沦为走狗
[lún wéi zŏu gŏu]
This literally means 'fallen into becoming a running dog,' which carries negative connotations, referring historically to servile or disloyal subordinates serving corrupt officials. Modernly it can be used self-mockingly, admitting feeling powerless caught between societal pressures, expectations or situations against better judgment. Caution: depending on context, it could be perceived offensively.