If you do not enjoy running or swimming, then cycling will do.
Whether you mountain bike or just ride the bike on your way to work, you will surely sweat!
I strongly advise you not to use city bikes (they are excessively heavy and uncomfortable) but to use your own bike, best if with gearshift, otherwise you won’t survive uphills (and you need them if you want to burn calories). You can choose to ride your bike every day for at least 30 mins or, if you have the time and know where to go, you can ride longer for a couple of times a week. In both cases, never forget to bring water and wear a safety helmet!