Ultimately, "saying no" is a skill like every other. One has to learn it and get over the uncomfortable feelings by regular repetition. Self-regulation is always handy in the workplace. We should not underestimate its power, even though we don't work as freelancers. As Friedrich Nietzsche pointed out: "One who cannot control himself shall be controlled by others. That is the nature of all living things."
When I was working on this article, I visited a couple of friends to see what was the worst thing that had happened to them just because they didn't know how to say no. My buddy, a bartender, triumphed over all. One afternoon, his boss came to see if he could take an extra night shift. He said yes. A couple of moments later, a boss from his second job called to ask him if he could take the morning shift. He also said yes, and this boss then asked him if he could also take the night shift too. He was embarrassed to say no, when he agreed the first time, he asked him and so he continuously worked for 34 hours straight. That must have been a record of some kind.
I still wonder if he made up the story, but I have a feeling that he is telling the truth. It is something everybody struggles with. Doesn't reading a job description in a employment contract after some time make you smile? It's always the same - colleagues or superiors come to you to ask if you could do something "just this once" and if that works the first time, they are sure to come back the second time and the third time... Yet, you still find yourself unable to say "no". As a result, you gradually realise that what you did at first as a favor is now your duty.
"Could you come in on Saturday?"
Why is it hard to say "no"? Like it or not, we are social animals. We want others to accept us. When modern man was born, he formed hunting groups and lived surrounded by wild nature and a mixture of delicious as well as dangerous animals. Being rejected in such a world means a bit more than locking yourself at home, crying in the pillow and watching bad movies. It meant dying of hunger. Being rejected in the workplace feels pretty much the same.
Saying "no" is hard and especially marketers, traders or con men are aware of that. I recall reading Robert Cialdini's “Psychology of Persuasion”. Manipulation often starts with us being unable say "no" to somebody doing us a favour. As a result, we find it difficult to decline doing a much bigger favour for the same person. Another way of manulipation is "framing", the term comes from behavioral economics (that's where the popular Kahneman comes from). People react differently if a task is defined positively or negatively. In Iceland, for example, organ donation is implemented this way. Everyone automatically becomes a donor and if anybody wants to be deleted from the organ donor database, they have to file a specific request. To say "no". I am sure you can imagine how effective it is.
Another one of my friends recommended the book "Crucial Conversations: Tools for Talking When Stakes Are High". In the book, the authors teach you how to formulate your answer in a way that asserts yourself and at the same time reflects the request of the other person. The book also lists a host of scenarios that can follow and what strategies to follow. See? - It's a complex thing.
Ultimately, "saying no" is a skill like every other. One has to learn it and get over the uncomfortable feelings by repeating it regularly. Self-regulation is always handy in the workplace. We should not underestimate its power, even though we don't work as freelancers. As Friedrich Nietzsche pointed out: "One who cannot control himself shall be controlled by others. That is the nature of all living things. "
However, bear in mind that your boss or colleague is a human like any other and maybe they do not want to take advantage of you but maybe they just want it to be clear. In that case, it is ok to say "no" because no one knows what's on your mind.