How do I get vivoactive 3 battery to last longer?

GPS uses the most juice. I have a VA3M and have about 4-5 days of battery life with bluetooth and heartrate enabled. The only compromise is using rails with seconds off and heartrate display off so the watchface does not get updated every second. Doing GPs gives about 8-9 hours before the battery is drained. 

Damn I did not know using seconds and heart rate on the watch face would drain battery.. now you’ve mentioned it , it makes complete sense. I need to use seconds on my watch for my job and also like to easily view heart rate so I might just have to deal with low battery life if I want these 2.. I may disable gps tho ! 
thanks so much for your reply 

GPS will only turn on when you start a GPS based activity.  It does not turn on by itself so there is nothing to disable.

Prior to the 6.90 firmware release, mine was configured with 30% backlight, Heart Rate always on, Bluetooth always on and communicating with phone so I could receive notifications, CIQ watch face (KISS) with no second hand and I would consistently get 16% battery consumption per 24hrs.  It typically went 5 days between charges if I did not use a GPS activity.  This to me is a good battery life better than most watches.  I'm hoping when I get 7.0 pushed to me they have fixed whatever they broke in 6.9 and I get back to that.  If you are consuming all battery in a day something is badly wrong.

before 6.90 I was getting even better numbers - also without GPS - but with 6.90 (and 6.94) I get max 22hours

I did a manual upgrade to 7.00 2 days ago and..... SAME so the issue is not solved with v7.00 . One thing though, the GUPDATE.GCD for 7.00 did not include the sensors upgrade which is advertised so it might be that the issue is with the sensors and the relevant upgrade will fix it but for that I still wait for the staged pushed which is still at 50%...

Thank you. After writing that comment I did notice that gps was something I could not disable. I have now turned my backlight from 30% down to 20%. I previously had a vivosmart 4. I would generally charge it on a Sunday and Thursday afternoon- I guess I was comparing it to that and since being told the battery life was 5-7 days on the Vivoactive I was a little concerned mine is draining too quick. I know the vivoactive is a very different watch in the fact I can constantly see the face watch and it has a colour touch screen so it’s battery life lasting 3-4 days is better than having to re charge every day! 

 disable bluetooth as much as possible for a few days to get an idea how much drain is from it, Then decide how often and when you actually need the bluetooth. 

I believe a most important thing to lengthen a battery life is - remove anything from a watch screen that is moving fast (seconds and way to many numbers on screen that updates frequently) and keep your cellphone in close proximity (so the watch bluetooth no need to search for lost connection or to re-reconnect). But again I am thinking right now I am charging my watch in another room and my cellphone is here with me, so that may be a distance of about 8-10 meters and the BT is not disconnected...Also charging the battery, when reaches 100% leave it there for an hour + longer, best for the battery.

I have a simple analog watch screen without second hand, the BT is always ON since day one but turned of all interactions between the cellphone and the watch (my cellphone is always in my pocket or right beside me on my desk anyway so why to get notifications on my watch to look into cellphone that I got a message???). I sync the data manually at my time, no alarm set, and the screen is locked, taking of the watch only when showering.

Just came back from EU vacation trip, every day I was logging GPS with a Walking app so I can plot my fun days on google map how and where I was moving around browsing city's, the battery lasted long enough to log 7.5-8 hours non stop GPS.

My ordinary days/weeks when not planning a GPS use I am charging the watch once a week usually Sunday's afternoon.

I have also tested my watch battery, when it is down on last 5% I am still getting one extra day out of it. At very last 1% the screen goes OFF and cannot wake it but the sensors still counting steps-HR-stairs-activity minutes whatever I set to monitor.

You could also turn off the automatic backlight (wrist turn)