Saying no is a life skill, and one that is very important to master. You should remember that it won't be pleasant, even when you have mastered it.
If every part of building a career or a business was easy and stress-free, there would be more successful companies and careers. Being successful at work (like being a good parent) is not a popularity competition.
Time to move on
The good news is that it doesn't feel terrible for long, so get over it. Those fleeting moments of discomfort as you faced down another inadequate pay rise, refused to man the cake stall at the school fete, or did not agree to run the London marathon for charity will result in a much better feeling as you scale the business heights you were always destined for.
So, how to equip yourself with the ability to understand when to say no and the strength of character to do so?
First, make sure you say no, and not some other phrase. The word 'no' should appear somewhere, even if surrounded by less harsh words: 'I am afraid I am going to have to say no'.
Second, don't leave the door ajar in any way. If you decline an event but say you can't do it 'this time', you will be asked again and will have to say no again. Much better to explain why you are declining the invitation, and say: 'I am very busy with my existing commitments and am only accepting invitations from charities I am formally associated with.' That way, they will know not to ask you again.
No to sex with a colleague, boss or client will have to be said as nicely as possible and with an explanation.
Otherwise, it will all be very awkward next time you meet. Best to say that of course, if circumstances were different and he/you were not married, working for the same employer, or whatever, he would of course be the man of your dreams.
It is definitely not a good idea to say what you are really thinking, especially if he is (a) senior to you and could be influential in your career and (b) what is going through your mind is that if he was the last man on the planet, chastity would still seem an attractive alternative.
Explain what you want
No to a financial offer, be it a pay review, bonus or a new job, needs to be said firmly, and unemotionally, but with a detailed explanation of what would produce a yes.
It is no good having histrionics when you get a substandard bonus, as this will only make people badge you as emotional. Instead, try explaining in a calm voice why you believe that you deserve a better bonus, give the letter back and ask if you could convene another meeting to discuss it.
Give up alcohol (or bread, or chocolate) for a week (or longer) so you can practise saying no. Get used to saying 'no' when you are offered it at social events. It will be a good way to experience the discomfort of saying no, all the while realising it is for the greater good.
How to get a yes
When approaching people who have learned to say no, make the request very specific and make it as difficult as possible for them to say no. People still email or call a headhunters with very little more than 'Dear xxx, my name is xxx and I would like to meet you to discuss my career'.
A much better approach is: 'Dear xxx, I met Mrs Moneypenny (or whoever) the other day and she suggested I email you my CV. Please consider me for any roles that you may have. I would welcome the opportunity to explain more about what I am seeking in my next role.'
By making the request clear and by including the name of someone who is known to and respected by her, you have a much better chance of getting a positive response.
Mrs Moneypenny's Career Advice for Ambitious Women by Mrs Moneypenny and Heather McGregor is published by Portfolio Penguin at £9.99.