Tomorrow Tim Kopra and I are going on our EVA (extra-vehicular activity). We have been preparing for this specific spacewalk for weeks in space, and months before that on Earth. However, to undertake an EVA actually takes several years of training. We have spent many hours working in our spacesuits, 'floating' in the largest swimming pool on Earth with a Space Station mockup. We have used virtual reality headsets to re-enact our operations and trained for the worst case scenario of becoming detached from the Space Station but I guess nothing can fully prepare for the feeling of being outside of a spacecraft in the vacuum of space.