I received VATS minimally invasive segmentectomy so it wasn't as major as lobectomy. Even my hospital stay was less than 1 day (approx. 20 hours from surgery).

I started walking as soon as I could. I very carefully got up from my bed and walked to the bathroom the next morning. The pain wasn't excessive but it wasn't pleasure either. I started feeling better quite fast and the afternoon after walking to the X-ray and having pictures taken I was released and walked unassisted to my brothers car waiting outside. I think I spent that and next day taking it super easy, mostly just lying in bed and not trying to hurt myself. But on the third day after hospital I already walked 3km (1.86 miles). On the fourth day I was feeling great and walked a lot more: 7,8km (4.6 miles). On fifth day I walked 4km, sixth day I was again feeling great and went spontaneously for a 12km hike in the hilly woods. While climbing the hills at some point I started getting really out of breath and got pain in my chest so I stopped, rested for a while and turned back. On 7th day 4km and on 8th day I started getting shoulder pain on the same side as my surgery. I didn't at the time attribute it to the walking after surgery because walking made me actually feel good. I rested couple days and then walked again and I got shoulder pains once again. Interestingly the shoulder pains went away when I walked so I thought I should keep doing that, but the shoulder pains actually got a lot worse in the evenings and when going to sleep. It took me trial and error to stop going for walks. After resting 3-4 days and not exerting my lungs or shoulder I started taking walks again and started feeling great again.

If you develop this shoulder pain, it's most likely due to the irritation to the pleura. Of course you should talk to your medical professionals about it. If it happens to you, my personal advice is: When sleeping, try not to lie on your back and instead try to lie on the opposite side from your surgery. This helps rest your shoulder and entire arm against the side of your body. Also for couple days try to move the arm as little as possible. Don't reach high (above your waist) with the painful side. Essentially avoid any kind of motion that makes your shoulder move. Rest for couple days and it will get better. Don't try to do stretches or exercises even if it makes the pain go away. It came back for me and it was worse than before. It's best that you let it rest.

Now it's been 28 days since my surgery and I went on my first run after it. Time will tell if I start feeling pain again but so far so good. Every now and then I still feel a pinch or discomfort. It certainly isn't what it used to be but all things considered pretty good.