So I'm running Watch OS4; original June 2015 SS 42mm Apple Watch. So on a typical day: I'll be at 100% leaving home, after an 8 hour shift at work, i'm either totally DEAD or holding on at 10%. After only 8 hours. Only very little use during the day; mostly check text messages and the time. What gives? I think I will upgrade to the 4 whenever it is released. Sadly.... I love the watch otherwise!