From the unconventional and awe-inspiring to the hilarious and heartwarming, here's a look at some of the most interesting photos, videos and stories that have our newsroom talking today. What's capturing your attention, filling your inbox and cluttering your Facebook/Twitter feed? Comment below with the stories you're talking about or tweet them to us using #InstantIndex and they could appear on World News

GENES, NOT LAZINESS TO BLAME FOR HATING GYM?

In a work-out crazed world, not everyone is wired to get that endorphin rush from exercising. Scientists at Iowa State University tested peoples' moods as they exercised and found that everyone's tolerance to pain factors such as heavy lifting or aerobics is different. The research suggests the physical effects of exercising such as heavy breathing, sweating and pain can trigger varying responses in the brain. The body's tolerance to the pain factors associated with exercise could be as much as 50 percent genetic. This means while some feel great during a hard workout, other may become moody and irritable. In these cases, the researchers suggest listening to music while exercising to help increase the mood.

SAVING THE 'REAL' PETER COTTONTAIL

(Getty Images)

A new program has been created to protect the native New England cottontail rabbit, the critter that inspired the popular children's tale "The Adventures of Peter Cottontail." Their population, once abundant, has now thinned out considerably as their natural habitat continues to vanish. Conservationists are restoring shrubs and even breeding the rabbits to make sure they're around for many more years (and many Easters to come).

JUSTIN TIMBERLAKE IS FULL OF SURPRISES

(ABC News)

Justin Timberlake sent fans on a scavenger hunt for his new album "The 20/20 Experience" on Friday. Five signed copies were hidden and five lucky fans found them with clues the singer was tweeting out. Other fans got a huge shock while they were shooting a commercial for his album. The pop star surprised his unsuspecting fans while they were belting out his song "Mirrors." Their reactions are priceless. The behind-the-scenes video was uploaded to Timberlake's VEVO page.