There will be all sorts of activities, music, fellowship, fine dining, sights to see, playing with animals/pets (most likely), discovery, creative activities (art, etcetera), and enjoying God's presence and fellowship unhindered by sin. (I also happen to believe that there will be sex in Heaven, though no marriage [there will apparently be no reproduction].) Of course, sinners [i.e. non-Christians] love sin, so for them it most likely wouldn't be all that appealing (no adultery, no lust, no rape, no murder, no stealing, no lying, etcetera).