Lifting weights or using nautilus help to build muscle strength but be sure to do some sort of aerobic activity as well. Getting started is almost harder than exercising. It will take awhile for your body to get used to the activity but once it does you'll find that it becomes more difficult to miss a day of exercise than it was to motivate yourself to start. So start by exercising your will and then your body will take over the task. Stretching is important to help prevent injuries.
Some people prefer to warm up before stretching and some like to stretch before their work out.
The idea is to include some stretching in your routine. Take it slow and easy, don't bounce.