Swimming is the perfect way to tone up you legs, waist and upper arms. Start slow for about 20mins steady pace lane swimming, 3 times a week. Then, keep to the 3 times a week, but slowly increase the time you swim for (say, 4 lengths more each week per session).
If you find that certain areas need more work than others i.e. your legs, use a small float to rest your arms and just use you legs to kick a few lengths in each session.
You will be amazed how effective swimming can be.
If not, try cycling around the country lanes near you - perfect for your upper legs especially if you have some inclines.
Good Luck :-) and have fun