I used to fold and leave the table feeling frustrated. Eventually, after playing many players heads up who try the "all-in" scare tactic, I knew I had to get over the fear. Now I fold a few hands until I have a hand that has a good chance of winning, and I call. I have discovered that it doesn't take long to gain some control at the table. Players who use the "all-in" too often have simply become conditioned to people folding or going on tilt, and so they typically are taking a chance raising with less than ideal hands.
I don't call a first "all-in" bet with anything but AA or KK, so if I have lesser cards, I fold. Once the opponent repeats the "all-in" betting scheme, I know that I have a good chance if I decide to call with any hand QT or higher or any pocket pair TT or higher. I may lose a few bucks folding until I have one of those hands, but the pots I win more than make up for lost chips. The offending player then does one of three things: 1) changes his/her playing style, realizing he doesn't want to risk another great loss, 2) leaves the table knowing that I am not vulnerable and looks for his next victim, or 3) tries the "all-in" strategy again, thinking it will work eventually. If he does the third and tries an "all-in" again, I leave the table because there are better games to be played.
With this strategy, you may occasionally lose, but odds
are in your favor; therefore, in the long run, your chip count should be much higher, as well as your confidence.