As you go up hill, keep shifting into larger and larger cogs in the back (less and less pressure needed to turn the pedals) until there just aren't any cogs left.

Then get off the bike and walk.

I've met lots of nice people while walking my bike up hills. It's a nice break. Take a drink or two of water, make a phone call to your beloved, sing a song, admire some gardens.

Life is good.
Ride your bike.