Apple Watch battery stuck on 100% all day

I got my first Apple Watch just over 1 month ago. My battery has been showing that it is 100% charged all day. Sometimes it just dies and shows me the charging cable on the watch screen because I have no idea that it needs to be charged until that point because it always says 100%. I have tried turning it off (just holding the side button) and back on again as well as resetting it (holding both buttons for 10 seconds) and nothing has changed. Suggestions?