Bring your own lunch (and even breakfast) to work. This will reduce the frequency that you have to eat out. You can have control over preparation of your own food, and you can often invest in healthier options. Not only that, you can usually save money. 

If you need to snack at work, try to avoid candy or carbohydrate-laden food. Try eating nuts, dried or fresh fruit or protein bars instead of sodas and candy bars. 

Drink plenty of water. Set milestones to monitor how much you drink throughout the day. For example, attempt to drink one 8 oz. glass of water by 10 a.m., another by noon and so on. You will be able to improve your hydration while avoiding sugary, unhealthy drinks. 

Keep a sanitary work space. Always wash your hands, and clean up after using common areas like break rooms. 

Commit to time away from your computer. You need to give your eyes periods of rest after staring into lighted screens. For example, eat lunch and take breaks away from your desk. Read a book or magazine during this period. 

Take work breaks throughout the day, if you can. This can help reduce stress and help you focus on your work when you return. Many companies even require employees to take periodic breaks. 

Move around. For example, take time during your break to walk around outside or do some stretches at your desk. This can help improve your muscle tone and circulation. 

Consider enhancements to your desk like a standing platform or posture straightener. These mechanisms might help you remain more active and engaged in work.