They say 'when the going gets tough, the tough gets going', but recently it has been re phrased to 'when the going gets tough, the tough hide'. Both are right. You ned to know when to act tough and when to hide ;) You need to know when to say No and how to say it. When you say a NO,

1. Be straightforward

2. Briefly explain yourself (don't fabricate)

3. Bring up an alternative if you can/want

4. Keep your stance