Cannot Vs Should Not

I got a feedback saying that I got difficulties in saying this word "Cannot"! I will always use "should not" instead. By saying "should not" am I helping the other party to have a backdoor or Am I trying to keep a image of myself ? Why I can't bring myself to say "Cannot" to others?

Cannot = No
By not being honest and say "cannot" , what good will it bring to me ? Am I going to live in the image of "nice" and torture myself to do things or even to avoid things when I don't like, just because I wont use the word "cannot".

What am I scare off? Scare to spoil my image and also being mistaken....How worst can it be? The more is be a bitch in someone's life and being mistaken, being judge... Anyway is not the 1st time being a bitch in someone's life...

I think I should come out with a movie of "No Girl" . hahaha....

• What is the new relationship with "NO" ?
• By saying "NO" does that mean negative impact on you?
• What does "NO" bring to your life?
• Is "NO" really a No-No thing in your life?

Sometimes saying No or Cannot , is the only word that I need to use so that I can get over and get thing done with. =)