My dad had a quadruple bypass 15 years ago so my experience is probably a bit out of date. He was out of hospital within a few days, wasn't allowed to drive for 3 months which was probably the hardest bit for him because he was very independent and used to being out of the house all day.
There was a lot of pain because he had a significant wound that was stapled so first couple of weeks he needed to stay pretty stationary and needed help getting up out of bed and out of chairs so he didn't have to end or strain too much.
There were meds which needed to be taken at the right times so it's important to make sure you fully understand the timings, which should be taken on an empty stomach, which with food and so on.
Dietary changes and exercise were then a more long term change, he was prescribed the gym and a specific heart healthy programme/club thing via the GP. Food had to be lower salt, lower fat and also he was on blood thinners for a while which meant being careful of vitamin K (broccoli and other dark green veg).
About a week after the op and for a few weeks thereafter he was very frustrated, he was starting to physically recover but not enough that he could do the stuff he was used to doing. In some ways he felt a lot better than before the op, he hadn't really noticed how lethargic and breathless he'd been getting as it was a gradual decline but he did notice how much easier he was breathing after the surgery. But he had the pain from the surgery and orders to not over exert and he did not like being fussed over or told he couldn't do something AT ALL. So he was grumpy, irritable and generally a bit unpleasant to be around, like an over tired toddler who kept whining about being bored.