Learn a simple plié exercise for a good posture, leg muscles, and Achilles stretch.
Want a GREAT ballet workout?
On Youtube, type in Ballet Boot Camp. There are about 11 parts focusing on abs, arms, butt, legs, technique, and some choreography. This is an excellent series for anyone who wants to combine dance with a workout. I like to start from part 3 and finish at part 11 :)
Another ballet inspired exercise routine is the New York City Ballet Work Out on Youtube. There are 9 parts, focusing on different muscle groups. E.g. abs, turnout, butt, and legs. Then towards the end of the entire work out series they have a "Reverence" section to focus on the dance aspect of ballet (which focuses on fluidity of movement and balance).
A fun workout that is appropriate for all ages and anyone who is new to exercise (however, first consult your doctor). I personally reccomend this: