I always tell my clients that the easiest way to get in a workout is to get outside and start walking or running. Its free, its safe to do on your own, and its effective. Once you are ready to kick it up a notch, you can begin to add in some exercises throughout your run. I always suggest picking 2 or 3 exercises that you are comfortable with and know you can do with great form, and mix them throughout your run to make a full body workout. Pick one that works your upper body, one for the lower, and one that works your core. Here are a few basics in each group.
Push ups (Easiest to incorporate)
Body Weight Rows
Plank Holds (Front and Side)
Lower Body (Be Mindful of Your Form)
Planks (All Varieties)