It does not matter whether you are a beginner or a pro at dynamic stretching. Some basics are swinging you arms in a out (giving yourself a hug) and kick your legs back kicking your bottom.
Tubing exercises are great for people with joint pain. The exercises are usually fairly low impact and do not require a lot of awkward bending or stretching of muscles.
There are a variety of exercises someone could do to help strengthen their calf muscle. Single-leg and double-leg calf raises are a great exercise for your calves as well as stretching and running.
http://www.momentumsports.co.uk/TtDynamicStretches.asp has a wonderful site onshowing you the best way to do your streches. They have warm ups and warm downs. This is a great site.
Try a library or a book store for books on exercises. Pushups are excellent exercises and free. Sit ups are great and free. First you should start with stretching exercises, which are also free.
A bowflex is a great fitness machine and set for beginners who are just starting to work out. It is a great product and I seriously recommend it to any beginners.
Applying the principles of overload and progression to exercise the joint.
They should do whatever they are capable of. Gentle stretching exercises and slow control exercises help a great deal. Loss of muscle mass is a big deal as people age so anything to promote and maintain core stability is a good thing.
Avoid doing exercises that impel high pressure on your knees. Going for a 30 minutes walk five days a week would be of great help. Jogging is a good one, too. After warming up try to do some stretching moves.
Yoga is a great way to exercise and strengthen the spine. Even something as simple as stretching can be used as a perfect spinal exercise as it allows you to relax the joints.
Betta's or Goldfish.
I would rather suggest stretching than traditional exercises! A carefully create stretching routine can help you alleviate pain/muscle stiffness while mobilizing the sciatic nerve! Combine some hamstring/lower abs/torso stretches, be careful when applying them (you need to follow specific guidance in order to make stretching harmless) and i am confident you will soon see some great results!
The following website has many videos on using exercise balls: http://www.fitnessmagazine.com/videos/exercises/exercise-ball.htm These videos are instructional and provide great how-to information for beginners and fitness enthusiasts alike!