Bicycles

The British doctor, writer, creator of the character Sherlock Holmes, Sir Arthur Ignatius Conan Doyle wrote:

When the spirits are low, when the day appears dark, when work becomes monotonous, when hope hardly seems worth having, just mount a bicycle and go out for a spin down the road, without thought on anything but the ride you are taking.

There is something about the simplicity and practical usefulness of a bicycle.