Get a big box of cheerios and a plastic box to store them in. Make them your "next to the computer" munchies. Switch from regular soda to Coke Zero and Sprite zero. Learn to eat salads for dinner, sandwiches for lunch, and something healthy for breakfast. Also, eat only oven baked potato chips.
And go shopping for some cute workout clothes to wear to make the workouts fun. Also get some small hand weights. I have seen soft ones encased in neoprene. Keep them at your computer desk. They make perfect fidget toys or stress balls, and they weigh around 2 pounds each. Working them when you feel fidgety will burn calories while you are sitting at your desk.
If you work on an upper floor, take the stairs instead of the elevator, if you can. Wherever you go, park farther out and walk in, whether it be the office, the mall, or your doctor or dentist.
Get a membership at Planet Fitness. It's $10.00 per month and they have a corporate policy of being trans friendly.