Find the biggest steepest naistest hill. Sit at the bottom and look at it. Then ride up it. Stand up and mash in a middle gear until you can't go any more. Then get off and walk the bike or shift into granny gear and pedal until you get your breath back. Once you get you breath back stand up and mash as fast and as hard as you can. Once you get to the top go back down and do it again. Anyone can ride a bike across a flat for miles and miles. Most people do not train to climb because it sucks. I have taken my bike up stuff people don't like to drive up because I train for the climb.