Chairobics

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So I think a large part of my problem recently has been my new job working 9-5, M-F in a call center stuck at my cubicle where our time spent away from desk is tracked very carefully so I am not free to get up and move around much. I just started working out again and for about two-three weeks now eating pretty carefully and I seem to keep gaining, not losing, not even in the slightest. I am very upset because I worked very hard a year ago to get down almost to my goal and maintained my weight at about 125 all winter, despite chronic lethargy and carefree eating. The sudden gain just took place in like the last month or two. I don't the stress from the job has helped, either. There was a week long layout the first week of April (they told us at the end of the day on Good Friday) and upon returning, everything was diff't. The expectations twice as high as before and I've really been stressed about it. In the last few days I have been researching ways to stay somewhat in motion while sitting there all day. My supervisor made the suggestion and putting a small waste basket on it's side and doing step aerobics of sorts with my feet under the desk. I did this today for atleast an hour in total and when I was doing it my heart rate was up and I would have to stop when on the phone with a customer because I was too out of breath to talk at the same time. I've also been doing leg exercises where I tighten my legs together and raise them up to knee level and then back down and I really feel it in my legs. I'm also looking into purchasing a small under the desk stationery cycle that you use when sitting (particularly at your desk). Here's my big question: How the heck do I track my calorie burn during a typical day of doing this periodically throughout the day!? I know it burned *something* and would like to add it to my fitness diary and not sure how since it won't really let me input just calories cause I could always give a smart estimate. Any recommendations?