Because time is too abstract to imagine we use space as a proxy. Past is behind, future is in front. We think of moving left to right along a timeline (if you're an english speaker).

Connections between visual and time perception. Far away lacks detail. Close up is more vivid.

One of the most common errors in thinking about the future is making it too much like present. We use present to fill in our memories of the past and as primary material for imagining the future.

Imagination - see future

Memory - see past

Perception - see present