A battery lasts an average of 5 years. The capacity of a battery decreases at extremely high and low temperatures. You notice this if starting the car seems slower or more difficult. Also very little use of your vehicle can have the same effect especially in the winter with short journeys with the lights and heater on etc.
Good charging helps
Has your battery been completely discharged? (e.g. did you leave the lights on?)
If so then make sure that you fully charge the battery, otherwise this will significantly reduce the lifespan. You fully charge a battery with an external charger (e.g. trickle charger) or by driving for about 1 hour on the highway without the radio, air conditioning, seat heating and other electricity sources being switched on.