It's all about sites.
Within the first fifteen minutes of my first trip with my first MD when I was 17, I found a lock assembly from an old rifle at Oglethorpe Park in St. Augustine (I don't even know if I was allowed to be MD'ing there or not

) ... and even with that freakish stroke of luck as initial motivation, I quickly realized that 'random metal detecting' wasn't for me.
I'm a hunter, not a meanderer. I love the thrill of the search, but am definitely an 'end goal' sort of guy and as such, prefer to know what I'm looking for. Digging garbage- be it contemporary or historic- with the off chance of finding something marginally meaningful doesn't even interest me much. Most folks would've put that lock in a little glass covered relic box and treasured it, I gave it away. I just totally, totally didn't care.
Finding a wedding band or a class ring doesn't excite me much either... but here in Chicago, I have a direct line on what's probably a modest cache- I could hunt that thing for a month straight with fire in my veins. Wreck diving? Man... Talk about something that really stokes my coals. Garage Sales... Flea Markets... Cluttered junk shops... Even browsing newly-listed ebay auctions in certain categories with "Buy It Now" enabled, lying in wait for that big, under-priced score... All treasure hunts that I love. Walking around a beach or a park with a MD hoping to find an earring? Not my thing. Maybe it isn't yours, either.
At least be open to the possibility that even if you master your machine, the process itself may not be for you. Treasure Hunting is about two things. Treasure and hunting. There's lots of ways to skin that cat, most of which don't involve chasing after pennies and pull tabs, hoping to hit something random. For those that dig the random metal detecting thing, right on! For those that don't, there's still plenty of ways to sate the treasure-hunting urge.