Is it unhealthy not to get sick (flu) often? haven't had the flu in 8 years and was told that its good to get sick each year. sounds silly, right?

Yes, silly: It's normal to get a couple colds a year, but it's not bad not to get them. You should prevent flu with the vaccine, but if you don't, and you don't get the flu, there's nothing wrong with that. But people who refuse vaccination because they 'never get the flu' aren't using good sense. That's like saying 'i smoke, don't exercise and eat a bad diet, and i haven't had a heart attack yet!'.