Keyword: Backpacking

The weight of your pack increases in direct proportion to the amount of food you consume from it; if you run out of food, the pack weight goes on increasing anyway.

The number of stones in your boot is directly proportional to the number of hours you have been on the trail.

The local density of mosquitos is inversely proportional to your remaining repellent.

The net weight of your boots is proportional to the cube of the number of hours you have been on the trail.

The difficulty of finding any given trail marker is directly proportional to the importance of the consequences of failing to find it.

The remaining distance to your chosen campsite remains constant as twilight approaches.

If you take your boots off, you'll never get them back on again.

When you arrive at your chosen campsite, it is full.