Bikes...hiking...you can even lay out yoga mats outside...find a place with tons of stairs...skating or rollerblading...jumping rope
Do stairs if you can find some, pushups squats etc in a park? There are plenty of thing to do outside. I dont have a gym but still manage (and if you have friends doing the same thing with you you dont get so many weirdo looks from others, lol)
U can try yoga.. i say sun salutation.!! Try it..