It means you love completely, without conditions, passionately, wildly, blindly, and without restraints, just like a wild horse that has escaped from a captor and is galloping through a sunny meadow full of fragrant flowers, looking forward and running toward your safe haven, and never even considering looking back to what you've lost.
The opposite of being "wild" is looking for drug rushes or engaging in promiscuity. Wild does not entail drinking heavily, loitering around a bar, and crashing your brand-new automobile in a cow pasture. Wild doesn't mean your gang sneaks into the school after hours, wrecks the hallways, and then bolts into the night while giggling maniacally. The theme of Wild is genuine adventure, whether it is physical or mental.
“Wild at Heart” is a book of 31 writers who have penned down their thoughts and experiences on different themes.