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

[delusionz]

The thermostat is likely stuck open.

Remove your thermostat from the housing, refit the thermostat housing and attach a garden hose to it and blast out the cooling system. Attach something to the top radiator hose to drain it out away from your engine bay and paint work. -- Blast it out until water runs clear, and turn on your heater so it opens up the flow through the heater.

After this, remove the thermostat housing again and refit with brand a new thermostat and gasket.

Refill with 2.5 liters of coolant and top up the rest with distilled water.