I learned the basics of snowboarding in an afternoon. Sure there was lots of falling and aches. Protective gear can help a lot though.

What’s tiring at the beginning is standing up all the time from falling so often. As you fall less often, you don’t need to stand up so often anymore and it becomes less exhausting.

With increasing skill you also need less muscle power to turn and stop.

When skiing/snowboarding you probably spend more time sitting in a chairlift than actually riding down the mountain. Then there’s waiting for friends, waiting in line, breaks for eating. I never measured the time, but you might not even get a full hour of pure skiing during a day on the mountain.

For learning I would recommend to first just go for a weekend and then later the same winter for a week. During the week take one day off for recovery. Some pain and exhaustion will always occur, but that’s just the way it is with any strenuous physical activity. Best practice for preparing to learn snowboarding is to lie on the ground and then stand up repeatedly.