Firstly let’s address the correlation between assertively speaking up and stress management.
When people say “yes” when they would rather say “no”, then the very act of taking on whatever it was that they said yes to will add to their load – whether that be time, energy, money or a combination of those. It nearly always means a sacrifice of some sort and often has repercussions, of which can cause stress. For example: your colleague asks for help, reluctantly you say yes, however that means your own work doesn’t get finished on time. That act caused you to let down your boss who needed your project to do his/her work. Another example: a family member asks you to “swing by the shops” on the way home, which was a significant detour and a much later arrival time, causing you to miss your gym class. The list of examples can go on and on. Constant losses of the things you really want to do, (due to saying yes instead of no), not only puts stress on you, it can cause resentment, weaken your self-esteem, and/or fester feelings of victimization.
Just to remind you of the definition of assertiveness – the art of communicating in a clear and direct manner with the utmost respect for all relevant parties (yourself and who are talking with).
Be mindful of your tone of voice, body language and the words you choose, as they should all be congruent with the message.
Here is a simple example that I’ve used. My neighbour was playing his preference of music very loudly late at night. There were a few options I could choose from – say nothing and be upset about it (passive), say nothing directly, but lodge a complaint to the police (still a form of passiveness), loudly bang on his door while screaming in a forceful tone to “shut the (swearword) up” (aggressive), or knock on his door and politely ask him to turn the volume down (assertive). The assertive option is what I did which was 100% effective.
If you’d like some help liberating yourself from always saying yes, get in touch here.