Bodyweight exercises sure work. They don't have to be boring either. There are tons of options for structuring a varied, interesting workout. Tabatas, intervals, curcuit training, you name it. I would suggest looking into some of the books by Ross Enamait: http://rosstraining.com/
Great stuff, definitely the real deal. Also personally tested by yours truly.

Personally, I hate roadwork. With my busted ankle I can still run a good sitance if I have to but I try to avoid the heavy impact as far as possible. I've been using a stationary bike for many years now and it's an excellent tool. Reasonably compact and it's always there, so no excuse for not working out! If I had more space I would certainly invest in a good rowing machine. An eliptical trainer might also be a good alternative.

The real challenge in my case is staying fit now that I have a desk job. I also couldn't agree more about eating out - no matter how hard I try I always end up eating more junk food than I ought to. It's downright appalling how quickly it affects my stamina - low energy, decreased stamina... Then working extra hours and getting back home late, feeling too lazy to do anything by the end of the day... Pretty much the beginning of a vicious downward spiral.

These days I try to do 20-30min. high intensity cardio 2-3x per week, ocassional heavy bag work plus as many pushups and bodyweight exercises throughout the day as I can manage. I also walk at least one hour per day (to work and back). Plus staying active over the weekends and holidays. Despite all the efforts I can't help but notice that I'm nowhere as fit as I used to be just a few years ago when I was still into combative sports.