Hi, after 2 weeks I was walking 3-4 times a day, surely a few km in total.
As Chuck says, if you have no explicit restrictions about weight bearing, walking is "the" exercise most recommended. Of course, you must build up gradually, very slowly, and always keep check on how things feel right after and the next day.
I found more comfortable standing than sitting for the first few weeks, so probably that's why I managed to walk a lot!
I took every opportunity to go out to the grocery shop and buy the milk/bread, little things. A trip to the post office to send a letter. Things like that.
It's true that between 2-4 weeks post-op there is a 'dip' for some (that was my case), one because the initial overdose of drugs wears out and you feel more 'things', two because you might lose patience when realizing there is still a long way to go and you must keep motivation high, three because you are a bit tired (sleeping is not easy), four you might miss your job (not my case!), five ...