While the distance travelled by light in a year (a "light year") is a significant measurement, there is one that has greater relevance to most of us: the "shag mile".
The shag mile (noun) is the distance one is prepared to travel in order to have sex.
Imagined SMS exchange*:
A: I am quite enamoured with you.
B: I feel rather passionately disposed towards you.
A: If only...
B: ...we weren't so many shag miles apart?
A: Yes, but it's a measure of my deep-seated lust for you that I will travel around 150 shag miles to see you.
B: I'll be waiting on the bed with my kit off.
*The real exchange would be considerably fruitier than this