Like the other commandments, Jesus expanded on them or defined them correctly. The Sabbath is not an exception.
I normally just think of what Jesus demonstrated acceptable work is on the Sabbath, it's actually quite broad. Jesus and his disciples gathered wheat, read the Scripture, did at least one recorded miracle that I recall, and authorized someone to pick up his bed.
The Sabbath, in my opinion, is pretty easy to keep and most of it I do anyway. Just keep it holy, be prayerful, do good, and so on. For a Christian, this should be a 7 day a week thing anyway.
The Sabbath is a particularly less worldly day, though, and I treat it as such. There are some worldly things I can do that aren't sins, but I may actually avoid them on the Sabbath completely. That's how it makes sense to me and it's a way to keep it holy.