The batteries in Apple Watch are very small in comparison to an iPhone battery. If you charged your watch yesterday and its still at 60% today, that's pretty amazing actually. It all depends on what you do on your watch. Things like downloading email messages, streaming music, reading and responding to text messages and of course making and receiving phone calls will all use the battery faster.
See how Apple measured the performance of batteries in Apple Watch. Scan to the section on Apple Watch SE --> https://www.apple.com/watch/battery/