GW2 is the type of game where you can take a long breaks and still have fun.
If you set small/long time goals like completing masteries and working on a piece of legendary, there is always something to do:
I'm currently working on getting a legendary of each weapon type and a full set of heavy WvW legendary armor. Currently have Sunrise, Twilight, Eternity, Frostfang, Moot, Meteorlogicus, Incinerator, Rodgort, Bifrost, Bolt, and Kudzu.
Finished my Chuka and Champawat not too long ago. I have the Vision, Aurora, and Ad infinitum. Currently have 3/6 piece of Legendary WvW armors. Working on getting the final 3 pieces as well as Conflux and Sleeping Conflux.
Everyone is working on the free Legendary amulet Prismatic Champion's Regalia so that's another reason to come back right now.
When I finish the heavy set it's time for the light and medium armors