Snowboarding becomes really fun when you can make turns.
I can't make any promises because everyone's physical strength and ability to exercise is different, but I really recommend a one-day lesson where you can hire a coach. (50,000 yen)
You can take lessons without worrying about time, and same coach will set the shoes based on your foot size and width.
You are free to decide when to take breaks and have lunch time.
Also do lessons that aren't on the snow, like checking your posture.
It's important to improve snowboarding skills.
This isn't an option, but you could ask the coach to record a video or take pictures during the lesson.
On the Snow Lesson up to 4 hours , Fatigue can lead to injury, so take adequate breaks.