Defenders enjoy defending, so when we're defending properly (and that includes the balance we get from both wingers defensively as well) the back four and 'keeper will be enjoying themselves more. Then the midfield and attack can go and express themselves more and the whole team is then enjoying themselves.
Whether you're Mourinho's Inter defending on your own six yard line not letting anything through like a brick wall, or you're Guardiola's Barça defending on the half way line winning the ball back after six seconds like a swarm of bees up near the opposition's box...defending properly is the key to success and the success of that will bring enjoyment!