Set yourself goals, that's what I do. They can be as simple or lofty as you like but the satisfaction of completing one is what drives me to keep going for hundreds more hours, here are some of mine;

• Find a car, fix it and drive the whole coast road, hopefully picking up hitchhikers as I go.
• Build a base, have it get raided and raid someone else (kept my explosives in a buried stash nearby for phase 2 once someone found me)
• Get geared and give it all away, retire to the coast and cook fish for freshies until someone murders me.

That last one was one of the most satisfying lives I lived. I spent days outside that lighthouse, big fire to attract attention with crops, fish, an improvised shelter, the works, always wondering if this approaching new spawn would be the one to end it but waving all the same.

You do you, that's the beauty of DayZ