tell people what you are doing, but that you would love to join them as soon as you are done exercising!

I still don't get to do it as often as I'd like, but I manage to make more time by splitting it up. Except for cardio, which requires time spent to reach the appropriate heart rate for benefit, you don't have to spend half an hour or whatever all at once. I stretch and go for a walk first thing in the morning, as a transition from sleep to getting my day started. Right after work, I do at least my physical therapy exercises and one body segment (upper, core, lower) of strength training, as a transition from business to pleasure. This also seems to have a positive effect on my stress levels and moods. Then, I can also do certain exercises while I'm doing other things, like doing situps, crunches, squats, etc., while watching tv, or curling the jug of milk while waiting in the checkout line grocery shopping. You like to use a stationary bike? Put it where you can do it anytime you happen to be watching tv, or get a regular bicycle and ride it for nearby errands instead of driving.

personally, i block out 30-60 minutes before work, 4 days a week. the nice thing about that time slot is that no one is going to be inviting me to have a beer or watch a movie at 8a, and it doesn't require very much effort to wake up 30 to 60 minutes earlier than i normally would.

an additional benefit is that if, for some reason, i miss my morning workout, i can fall back on my lunch hour.

Suggestion ... just substitute the time that you spend on the computer / Internet with some sort of activity that isn't so sedentary. Get outside and walk. Walking helps tremendously.