fartlecks...(I hate doing them but they are great for endurance and calorie burning)...we do them for track workouts.
-1 minute at almost a sprint then 2 minutes at a jog. you would do this for 20 minutes or 2x15 minutes...after a proper warm-up
-when you are just starting out, go for about 30 seconds sprint than 2 minute jog.
(you can do this with walking, but with jogging than walking)
you can also use weights when you walk/run so you can tone your arms.
notes:
you should be sweating before you actually start working out, so your warm-up should make you sweat.
stretch after your warm-up and work-out
when you tighten up when you run try running backwords for a couple minutes.
to prevent muscle tightening...take in electrolytes...drink water (make sure your well hydrated), and if you injure any muscles eat protein...nuts, beans, meat, etc.