It's a dark and stormy night. You're driving in a part of town you don't know well and suddenly, your car tire blows! Thankfully, you are rescued by the kind people who live nearby. They fix your flat and send you on your way. You are extremely grateful. Is there a proper way to thank them?
Of course, you can always verbally offer your thanks in the moment but if that doesn't feel like enough, make a mental note of the address and perhaps you return and slip a card in the mailbox or send a flower bouquet.
The key point to remember is this: There is power in offering a genuine, sincere and heartfelt, "Thank you." So when you've been helped by strangers in your time of need, your words are often enough.