In professional life, there is no one with whom you cannot share your sincere opinion. But, there stays few people with whom you shall never fight. Identifying such right people at right time is the most important job. Later, respecting your own choices is tricky. Because the moment you decide not to fight you lose the opportunity of winning things your way with such people.
Changing choices is always a choice but then your personal integrity comes onboard and wouldn’t let you do the same; may not be every time but definitely at times.