Is putting shingles on a roof hard?

I think that one of the biggest obstacles you'll face is the amount of physical work you can endure. Climbing shingles up a ladder isn't easy. You need to figure out how you're going to install the first few rows of shingles on the lower edge of the roof. Even on a rear roof, you can install a roof lift placed in the roof plane and stack bundles of shingles.

If you place a finished waterproof membrane or other underlayer on the bottom of the roof and, the next day, you still have to remove the shingles above it, the old shingles and nails can damage the products you installed as they slip across the roof.