Electric bikes aren't motorbikes or even mopeds - instead, they provide power on demand, responding to and complementing your pedaling speed and power. The harder you pedal, the more power the engine gives back. Most e-bikes provide up to 150% of your own power with each pedal stroke. Most also have three settings--high/medium/low--and off. You should still prepare for your time in the saddle, but you'll have more reward for your efforts.
More about e-bikes
Tours with e-bikes