"Running with the pack" is an idiom that means to follow the crowd and go along with what others are doing. There are various other synonyms that have a similar meaning, such as "going along with the flow", "being part of the in-crowd", "falling in with the crowd", "being one of the gang", "tagging along with the group", "being a follower", and "joining the herd". All these expressions describe an individual who is going along with the majority and not taking a different path or making independent decisions. It is important to think for oneself and not always blindly follow others.