How people feel about us is a direct result of the way we behave towards them, so the more positive that behavior, the more valued we are as a boss, colleague, member of staff, or friend.
'Please and thank you' are never overused words and should be expressed freely in the workplace. Being well-mannered and polite will help add and elevate the value of your work performance.
Assertiveness can sometimes be confused with Aggression, so it is important to strike a balance by being thoughtful of others around you.