How do you accomplish this during work hours? Isn't that stealing time or are you salaried/self-employed?
Matthew beat me to it, but just to add a few points ...
Salaried, and in fact I tend to put in closer to 50 hours for my 40-hour-per week job, easy, sometimes as high as 60 ... so spending an average of 45 minutes per day doesn't come close to offsetting the OT I put in. Being salaried and therefore "exempt", I don't get paid for OT, but the tradeoff is that on some weeks when we're slower, I also get my full pay. This relationship, however, tends to always heavily favor the employer, as at most companies you're RARELY ever found lacking work to do for at least 40 and then some.
On top of that, it's understood that people are productive for approximately 32 out of a 40-hour week and all "billing" tends to be adjusted that way.
To say nothing of the fact that eveyrone takes breaks. Company encourages people to get up and walk around for 10 minutes per hour (a new health thing to avoid issues due to being excessivley sedentary). I assure you that I spend less time online than most people do shooting the breeze around the water cooler about sports, politics, and other issues ... AND surfing the web on other matters, doing online shopping, etc. Those folks get caught up on conversations where I'd hear them talking about the same thing a good hour later.
Finally, software development requires mental breaks, it just does. You absolutely cannot focus at 100% attention for 3-4 hours straight, and if you try you actually get LESS productive over time. That's why a lot of IT people do weird things like shoot monkeys around on rubber bands, etc. I can't tell you how many times I had gotten stuck on some programming task only to immediately have the solution present itself 30 seconds after I walk to the restroom. Sometimes just a change of scenery un-sticks the mind when you get into a rut.