We need be courteous to all. There are all types of people. some have the tendency to interfere in every matter. This is not their fault. It is best to listen to everybody but do what suits you more.

Too much of interference will be an impediment to your own regular work schedule and blocks your progress. Such interference should be stopped with courtesy also. In spite of this, if the people continue to interfere, then there is nothing wrong in taking a harsh step.

If you just listen and don't argue but take your own decision, you save much of time and energy and also maintain relation. Also such persons will know in due course that you only listen but don't follow the advice, they will stop interfering.[/quote

Yes. The end result should be to make the person realize. In this process, it's up to the person to choose an appropriate way to put an end once and for all the uninvited interference.

I know it is very difficult to deal with people who try to pull you down. I have faced it, and to be honest, here you need to use the tactic tit for tat...being nice and polite won't help here.
Initially, when there were such people around me who used to do that I would stay mum but later on fight it within my head, eventually get stressed being around such people. Such people need to be given back with the same amount of criticism. You may not like it at the beginning, but slowly it would feel better. At least it is better off rather than cursing ourselves as to why I couldn't give a strong reply to what s/he said.

You may not agree with what I said, but this is my way of dealing with such people. I am cultivating this bit in me to give it back at that moment rather than bottling it up until i burst!

There is no one single solution since people are different and their attitudes are different and our equations with them are different, so we need to use common sense and prudence while dealing with people who seem to interfere again depending on the situation ...

About people who try to or actually interfere too much in our personal matters, I believe it is up to us where to draw the line. We need to decide whether we really need to answer everything the other person wishes to know or not. After all why do we need to explain ourselves to people who hardly matter to us.