One idea.. but it’s not too terribly much different than living your life.
Two possible futures stand before you. You decide which one you will enter into. Look at the time, add 1 minute. Soon it will be that time. If you get off your seat and do 3 jumping jacks. You will soon be in a future where the time is T+1minute and those 3 jumping jacks are complete. But there’s no turning back. Your other option is of course to just sit there and soon it will be T+1minute and those three jumping jacks will not be done.
Either way, you’re in the portal right now. Soon you’ll be out of it and experiencing that future. You can replace 1 with whatever time extension you want. You can replace the jumping jacks with whatever activity you want.
hopefully this made sense.