I'm developing my persona and I like and enjoy some themes such us mind reading or thought transmission. I have found a problem though and it is that I don't really believe in them.

As long as the routine is done the way I wrote it, without many interruptions I don´t have difficulties, but it has happened to me that after (or during) the tricks some people start adding more information or asking questions about those topics and I feel that I step out of my character and I start talking as a non-magician.

Do you think a magician should "act" their character all the time or just while he is performing?

Do you think I will overcome this kind of problems when I've developed my character better?

Don't do them if that bothers you.
Do magic that you do believe in, like levitation, or color changing card.

My philosphy has always been that you stay in character whenever someone asks you anything pertaining to magic or the magic that you do. My character is an exagerated extension of myself, so for me, it is very easy for me to jump directly into character amnytime I feel I need to.

One must be comfortable with the character you become and are portraying to the audience. You must also know your character so well that jumping in and out of character is second nature. For some, writing down a bio about their character helps them to get to know the character better in their own mind.

Kyle

For more on this I recommend my book Theatrical Magic, but a good solid character is going to be an outgrowth of your own personality - whether an amplified version of your self or a separate persona. So, whether in or of of character, you will maintain a certain degree of that character.

When I started out as BDC, he was a separate character that I put on and took off. Over the years he has become more and more integrated with the offstage me. Almost to the point that I am almost always in character if in public.

My personal experience is to leave the character on stage (usually).

Working a lot in the comedy club circuit, I found it really annoying to deal with other performers who didn't know when to turn it off. The same is true with magicians.

I have many on stage personas depending on what type of show I am doing. Off stage, I usually prefer to be a polite business man when dealing with other adults.

I haven't seen many mentalists and the ones I have seen seem to pretty much be themselves and just go into character when attempting thier feats.