Maybe make your movements matter while at work....if you need to stand, reach, twist, bend etc. put strength, feeling and focus into what you're doing. Go beyond job description if you sit a lot...start cleaning or organizing something while getting your job done. Take healthy meals, water etc. with you. If you have unhealthy stops on the way to or from work (picking up lunch (fries, burger, double latte mochachino w/ extra cream....whatever these stops are for...tell yourself before leaving that your going straight home, not negotiable and you will have a healthier chioce when you get home or where ever you're going.)
I used to work at a job where I sat a lot, I tried to stand and move as much as possible, every movement I focused on, I stood tall, stretching my body up as I stood, making all of my movements with precision and quality...but I skipped the part of eating healthy. But boy did I ever feel good when I was doing this & kept myself pretty slim for the amount I was eating (Burger King etc...99% of the time.) Plus 8-10 Lrg. coffees and countless other junk in a 12-15 hour shift.
So I am a firm believer that no matter what you are doing (working, no exercise equip., don't like to exercise, no time etc. you can lose weight as long as your moving with feeling, feeling the strength that you already have in your body...you will add to this as you go, move with resistance, stand tall and eat & drink as healthy as possible, as often as possible. After adding resistance to your movements, release when you feel comfortable to do so.
Don't go through life resisting all the time....do as much as you can in the movement, then release.
The next movement do the same...and so on.
AND...and this is a biggy.....think positive as much as possible!
I just wanted to add that at first, this may feel rather robotic at first, but as you go, your movements will become more fluent, you will be gaining strength regularly...not just once a week when you can and IF you can make it to the gym...it will be a constant, positive thing that will enhance anything and everything else that you do physically and/or mentally.