I'm getting close to 26 million exp and play in Michigan where playing outside can be challenging (lots of driving around in the winter). When I hit 40, approximately 8 million exp from evolves, 6 million from catches, 2 million from eggs, 1 million from battlegirl/training, and the remainder from pokestops. My guess is most level 40s who grinded a bunch have a similar ratio (maybe more eggs and fewer from battling). As mentioned by some others, this is only really feasible if there are a lot of pokestops and natural spawns in the area. I relied heavily on my Go+ (~two batteries a week); it was boring, exhausting, and I used around 200 lucky eggs from 38-40 but I'm glad I completed it as it was a personal goal to hit the level cap before 2017. My biggest tips for hitting 40 quickly, assuming you live in a place that has plenty of stops are to stop following scanners (too much time), stop interacting with gyms (too much time), and make a daily exp goal (mine ended up being 300k/day). Regarding integrating this ridiculous play time into a work/school schedule, I am about to finish my phd and during the final stretch of hitting 40, I was putting in 1 h in the mornings, 4 h at night after lab and 10 h on Saturday and 8 h on Sunday. It also helps that my wife plays as much as I do (she is 40 too) and that we don't have any kids, yet. Good luck!