The 70-200mm 2.8 IS II is HEAVY as! Obviously not as heavy as those primes, but it's pretty damn heavy!! Going to tell you my experience (might be a very lengthy post but it explains my experience with the weight of the lens).
I bought my 7D as a kit lens from the motherland of canon and nikon; Japan, (so my kit lens was a 18-200mm 3.5-5.6 IS). This was my first SLR camera and I thought the lens and the camera all up was heavy! Probably weighed about 3kg or something, give or take. Anyway I go to a major sporting event every year (tennis) and I almost go the entire 14 days of the event. Now I go there on average 8hrs a day. Since this particular tennis event is the weakest outta the other major ones available (i.e. one arena and lot pf practice courts is on one side of the venue and the other lot of practice courts and other arena on the other side, about 4.5km-5km away from each other. I would always have my camera hanging on my neck and if I was in one of the showcourts trying to get a player's autograph (i.e me standing on a platform looking *down* at them and leaning over the barrier, camera + lens dangling and swinging everywhere. It KILLED my neck. But not as much as the 70-200 lens did, it absolutely KILLED my neck 100x fold.
EVen though I bought a diffent strap which got a lot of reviews saying that it takes the weight (IMO it takes *some* of the weight) off your neck making it easier to carry. If I was not a tennis nut and devoted fan and keen amatuer photographer I definitely wouldn't recommend carrying the 70-200mm 2.8 IS II lens on your neck and using it to take take photos for more than 2 hrs, 3hrs at the most! I'm dumb lol, but hey, I really like photography and
tennis. I suggest getting a tripod (I'm in the process of getting one) and a few people said, before I bought my lens, was to go to the gym lol. It makes sense, but you definitely need
a backpack to carry the 70-200 mounted to your camera. Just using a tripod to carry it would be tiresom. Seriously try carrying a 10kg backpack with a 3litre hydration pack + food + jumper + wallet + some other things + books + pens&markers AND have 5kg (give/take a bit) of camera gear hanging/swinging/bumping/dangling down your neck for 18+ hours, walking god only knows just how many kms I walked on average a day during the event (at least 14km, the very least I reckon on average). Average 60,000 people/spectators are there at the event constantly bumping into you. Be prepared whenever you use your 70-200 lens, it's damn well heavy ESPECIALLY if you're silly enough like me lugging it around your neck for 15hrs a day.
BTW congrats on purchasing the lens, though I'm curious to why the original owner sold the lens