An in-built timer that warns how long of an interval you have been playing.
From the moment you launch a game, a timer should begin that will just notify you when you have been playing for a certain amount of time that follows the safety guidelines to avoiding VR sickness.
I know my boyfriend using our new headset doesn't feel ill when inside and just plays his way through for a really long time and I have to come out periodically when I think he should take a break for his own health and safety because I know after it's off he feels it.
It would be good to have a timer in game that just pops up to let you know how long you have been in for people who do try and follow those guidelines. Not just for the Quests either, but for all the headsets.
Or at least an Alarm clock we can set, so that we know when it's time to stop.
Time flies when you're having this much fun :)
But a counter would also be great, so that you can look at how much time you've been on. Be cool if you could see time in each app individually too. I think the MOVE app might do that now :).