You might be surprised to find out that some people find it difficult to say 'no'. Perhaps they think it's rude, impolite or inflexible. It's not. Of course, it's always good to show a collaborative spirit, to be open to change, constructive criticism, and to do things that are in the best interests of the group (within reason).
However, if something is clearly negative for the person involved, it's important to be able to have the difficult conversation; to say 'no'; or ask for what you really want (e.g. more money, time, responsibility). With that in mind, you have to find your own comfortable way of saying it - here are some examples:
- Soften it up by framing your response. For example, 'no, I won't' doesn't sound quite as nice as 'I see where you're coming from, but I'm not fully convinced it's the right path. It's a 'no' for me.
- 'Not right now because I'm in the middle of something which is also urgent. I'll come back to you on it later.'
- 'Sorry I can't, it's not part of my remit. I'm really trying to focus on my main responsibilities'.
- 'No for now. Maybe next time. I'll let you know if anything changes'.
You may feel that this will weaken a relationship on some level, but really it will (often) strengthen it because the other person knows that what you say is what you mean. Also, it means you'll be better able to focus on the important things.
Of course, with any communication, it's always important to speak in the right tone of voice and use the right body language etc. And it's always worth getting a second opinion from a friend or colleague.