not let people take advantage of me

My colleague asked me the other day if I would like to do one quite boring ask, which was actually not even my responsibility; he tried to sell it as “thats a cool thing for your experience”. I resisted. I didnt dare to tell him in person, so I just mailed back, no, thank you, I am working on something more thrilling. Seems like people respect you more when you are not a YES-man

Yesterday someone tried to give me extra task, which, according to my new job describtion, shouldnt be my responsibility any more.
The Old Me whould have done it without even expecting gratitude. The New Me committed that it should not happen anymore.
I tried to be politically correct, professional and at the same time firm.
I mailed back :
“In search of solution for all of us, I’m committed to assist anyone who is willing to learn how to get the data. At the same time I will do my best to prevent old tasks bouncing back to me due to the fact that no one else is able to execute them.”
Feels like small victory!