For a healthy heart, I've got myself into a habit of stopping by the gym after work and using the fitness equipment (treadmill, stair machine, etc.) or using the stationary bike I have at home.
However, I'll have a vacation in the future where I'll be in a foreign city for a few weeks. I won't have access to a gym or fitness equipment. I can take a pair of running shoes, but I don't think I'd like to run in a foreign city, and I'm not much of a runner.
So, aside from running, what other kinds of cardio exercise could I do while on vacation, say, from the comfort of a hotel room? I know sit-ups are easy but could those be considered a cardio exercise?