Battery life lasts less than two hours Apple Watch Series 3

I've had my watch for less than 9 months and recently have had problems with the battery. from one day to another, my watch went from lasting all day to just two hours or even less. this is without making any changes on the settings or installing any new apps. I don't listen to music on it and hardly ever use it to receive phone calls or text. I tried force restarting it but this did absolutely nothing. Would I have to take it into apple for service or what else can I do?