Go and kneel on your kitchen floor. Get up every few minutes then kneel back down. Do this for a few hours. Now get up and rub your hands in cement for a while. Go wash your hands, then rub in more cement. Repeat off and on for about 2 hours. Now go and do the floor kneeling again. Go and do the hands in cement for a bit again. Then go and pretend to clean your tiling equipment outside with the hosepipe - if it's not raining, get someone to pour water over you while you clean the tools.
See what state your knees and hands are in the following morning. (Knee pads are essential but they won't stop you getting knackered knees.) Now are you sure you want to be a tiler?