Travelling at the speed of light would have taken 0 seconds for you, the traveller, but 5-20 minutes for your observer.
However, the Lorentz factor at 20% of the speed of light is ~1.02. This means the distance you travel is only about 2% shorter, so relativistic effects aren't the reason for the discrepancy.
However, the Lorentz factor at 20% of the speed of light is ~1.02. This means the distance you travel is only about 2% shorter, so relativistic effects aren't the reason for the discrepancy.