An excellent exercise for getting yourself in better shape is walking. To increase the fitness benefit, take each step with your heel before your toe. This gives your calves more of a workout. Also, move your arms side to side, to improve flexibility and endurance while walking.
To improve your fitness, try working out a little each day. This is more beneficial than just doing an exercise 'binge' once a week. Incorporating exercise into your daily routine will make it easier to keep to your exercise momentum going, and means you won't dread and try to avoid an overly long workout session.