What to exercise if there is no gym in the hotel?

So, let's say you are staying in the hotel and there's no gym. Also, there is no park for you to jog. What exercise should you do?

Sit-up? But how many can you do to burn your calories?
Pilates? That's good too. It helps to strengthen your core muscles. Unless you can do the hundreds, if not, you can't burn much calories.

So what else do you have? Well, if you are staying in a hotel that is reasonably tall, I will encourage you to walk up the stairs. Yup, walk up the stairs. That's right. It is a good opportunity to strengthen your cardiovascular muscles. Take your time to walk up the stairs. If you have stamina, walk at least 3 times. Walk up and walk down. If you can't accomplish even 1 round, just relax and stop. Don't force yourself.

1 round is equivalent to 1 up and 1 down.