Boosting Energy Levels at Work
There are a few body exercises you can do to help give you more energy. One of the best ways is to stretch. While sitting for long hours, we tend to slump/round over, with our backs and shoulders rounding forwards. So look for any exercise that does the opposite.One is as follows:

Raise both arms above your head. Hold on to one wrist as you stretch and pull upwards gently. Keep your neck straight, avoid tilting your head downwards. Hold this stretch for 30 seconds, and repeat three times.
Next move on to a spine stretch

Stand up straight, and bend to the side by running your hand down the outside of your leg. Keep the movement slow and fluid. Repeat to the opposite site. This is a good mobility exercise for the lower and upper back. Hold each stretch for 10 seconds, and repeat three times.
Next do the chair rotation stretch

Sitting down in an upright position, rotate your upper body by moving your hand towards the opposite side of the chair back-rest. You can let the head follow, but progress by keeping the head straight forwards, thus making the rotation stronger. This is a great exercise to do while sitting for long periods of time if you feel your back is getting stiff. Perform 10 rotations to each side. The problem after lunch is that it's when most of us feel sleepy. Our bodies are digesting the food we have put in, and so our energy levels are low. Our minds are not focused and we start to feel sleepy, usually around the 3pm to 4pm time frame. So what can you do to feel less tired? There are a few things you can do. The best is to go for a 10 minute brisk walk outside. It needs to be outside, as the fresh air rather than air conditioned air will help revitalise you, but also being outside is generally more interesting and will help wake you up. Walking outside will get the muscles working and wake you up, breaking that sleepy pattern. If you cannot get outside, then try a couple of exercises.
Also, try standing up to work.

Standing desks are becoming more common to help posture and prevent back ache, but they also help to keep you alert, as you will feel less sleepy when standing compared to sitting. Also, have you tried sitting on a Swiss ball? Not only do they help posture, but they make sitting more fun! You can also do exercises on them too. Try to sit on a Swiss ball for about 1 hour per day. Sit on a Swiss ball with good posture, and roll your hips in a figure of eight pattern. Perform the movement in one direction, and then the other direction. This is an excellent lower back mobility exercise and also good for core control. Do this for 2 minutes.
And what should you do when you get home? It's really tempting to get on the sofa during the evening and spend a few hours watching TV, but try to avoid it. Limit TV exposure. Think that you have probably spent a lot of your day sitting down (commuting, work, commuting home, eating) and then you come home and sit as well. The evening is a great time to get some exercise. Try a static bike so that at least if you are sitting watching TV, you can get some exercise too. Try 20 minutes of cycling 3x per week on the static bike, it’s great for your cardiovascular system, and will stop you slumping on the sofa.