Temperature Gauge, Seems a bit too low? Options

[Serhey]

my temperature gauge always seems to be a bit too low, now i know its not good for the car to over heat but i also dont think its a good thing for it to be under. Now the car runs fine, atleast as far as i know, ive driven and owned cars before this celica, and it doesnt seem to act any differently, accelerates fine drives fine even driven it for 5 hours at a time and it was fine (i've only owned it for 2-3 months) but whenever i drive it the temperature gauge on average stays maybe 1/5 or at best 1/4 of the way up, way below the middle. could the gauge itself be broken or is it something bigger then that?
i've also turned off the heat to see if it had any affect on it and it seemed to go up a tiny bit but thats not the way i want to fix it

[IBTINTN]

I had the same problem with my Celica. Driving around town the temp would rise to almost half way. As soon as a hit a speed over 80kms it would drop down to just over the cold mark. As everyone has said change the thermostat. Mine was broken and when I put a new TRD low temp in I had heat again. Never had a problem since.