The definition of "being assertive" that I go by is to express your own needs/wants clearly. I agree that there is overlap with selfishness. That's because expr

The definition of "being assertive" that I go by is to express your own needs/wants clearly. I agree that there is overlap with selfishness. That's because expressing all of your needs and wants can upset others, and you know that it's not realistic for you to have everything you might want, whenever you want it, and that to try to make that happen would mean taking from others. However, I would say that there definitely are times when you can express what you want, and not take away anything from anyone else. I would also say that in some situations, it's a matter of protecting yourself, avoiding committing to projects you don't believe you'll be able to deliver on, for example. There are people who are not assertive, and say "yes" to everything to try and avoid upsetting others. However, they end up taking on too much and not delivering, which is harmful to others in the long term. In that case, being assertive and saying "no", might seem selfish in the long term, but is actually beneficial for everyone in the long term.