1) Find two objects about 50m apart. Do 1 situp then sprint the 50m, do 2 pressups and sprint back, do 3 and so on. Do this upto 15 and you`ll be sweating. You can do this with any exercise like situps, squats etc
2) Google some callisthenics exercises. You can make up a routine of situps, pressups, wide arm pressups, squats, dips, dorsal raises, russian twists and so on and do it in the house (or the park if you don`t mind funny looks)
HTH