Well tuck it in is not a good concept at all. It creates increased muscle tension around abdominal region and can be a contributing factor for low back pain.
In this article the author had mentioned a lot about exercises but I think ergonomic adjustments of your work place is also as important as being active, to reduce the amount of stress in body.
Alarm clock concept doesn't work either, imagine you have a dead line for an assignment and every hour an hour a alarm goes off to remind you to do exercises how would you feel?
Being an occupational health physio I have found that sticky notes on a corner of your screen works better.
