This is by far the most common complaint I hear.
If this is a challenge for you, concentrate on getting small workouts in throughout the day. If your job takes the majority of your time, consider taking 3-10 minute breaks and walk at moderate intensity, where you break a little sweat and are slightly out of breath.
Taking these breaks are not only good for physical health, but also for mental health.
You will go back to work feeling refreshed and satisfied.
If home life consumes most of your time, consider doing squats or other muscle toning exercises while doing housework.
If you work from home, use a stability ball instead of a chair to sit on.
Walk on the treadmill during conference calls.
These are small changes that can make a big difference in overall health and weight loss. And remember:
Doing something is better than doing nothing!