I agree.

Say yes when you mean yes and are wiling to make the commitment that comes with saying yes. That doesn't mean there is any guarantee against something unforseen happening.

And just as important, say no when you mean no.

When someone tells me I'll try that means to me the opposite. It means I'm really not all that interested and I won't make a commitment to you about this.

I think people say yes because we don't know how to say No. We think we are responsible for the other person's feelings that could arise from our saying No. So we say yes and sometimes even forget we say yes because we were never committed to it in the first place.