Yes, they have to cut the internal abdominal muscles in order to get to the prostate, and that's what takes the time to heal, and you don't realise how many things those muscles are used for until they aren't there!
I had an operation which involved cutting the same muscles, and my experience was that it was around 4 weeks until I could drive short distances (the "rules" are that you shouldn't drive until you can safely do an emergency stop), but a good 3-6 months until I could resume strenuous physical activities. Take it easy, and listen when your body says "that's too much".
All the best,
Chris