Beware of the dog eat dog theory where everyone else is fighting just to get ahead. This is where non-appreciative people usually thrive. No one will appreciate your contributions even if you miss lunch and dinner, and stay up late. Most of the time you get to work too much without getting help from people concerned. Stay out of this, it will ruin your self esteem. Competition is at stake everywhere. Be healthy enough to compete, but in a healthy competition that is.