Should people learn to say "NO" more often?

[Ja sa bong]

I believe a lot of people are struggling with knowing when to refuse doing anything for someone. As a result of this, such people take on the burden of others together with their own and it makes life miserable for them. Such can actually make them depressed because they don't want to fail whom they couldn't say no to.

Do you think saying no to some people should make you feel bad?