When you're going to exercise it's vitally important to warm up before hand and then cool down afterwards. This helps to increase blood flow around the body, which allows our muscles and tissues to move more freely and can help with wear and tear.
This can include light aerobic activity such as cycling or brisk walking/relaxed jogging followed by gentle stretching exercises.
Warming-up stretches your muscles and joints, making them more flexible with less likelihood of injury. Cooling down after a training session also helps to avoid injuries, as it assists the body to dispose of waste products that have built up in the muscles while exercising.
No matter how pushed for time you may be when exercising make sure you include your warm up and cool down.