Dental floss makes a perfect heavy-duty thread when you’re away from home.
Let’s say you’re on a long hike and your backpack strap rips just a little. This can throw off your posture, slowing you down. Even a tiny tear will likely only get worse. Stop it right away with some old-fashioned sewing skills. The best thread you can use is dental floss (you do always pack floss, right?).