The early bird
The most obvious way to find more time in your day is to get up earlier. If you normally set the alarm clock for 7.30am, set it for 7am instead and use the extra half hour to go for a walk or take part in some other form of physical activity you enjoy.
Alternatively, if you're not an early bird, consider looking at how you could use any free time you have in the evening to increase you activity patterns. You might want to look for a gym that's open 24 hours, or buy some home exercise equipment so you can work out while watching the television or listening to the radio.
However, it's important that you listen to your body. Our natural 24-hour biological cycle (circadian rhythms) means we experience exercise differently at different times of the day. Most of us know whether we're a 'morning person' or not.
If you find it hard to get up in the morning, don't try to exercise then as it will be difficult to stick to your new routine and won't enjoy what you're doing. It's important to exercise when you feel at your best for physical activity. Experiment to find a time that suits you.