Lack of activity working at home?

For those who are work at home parents....I'm a WAHM 2 days a week during the summer. I feel like such a schlub...I'm sitting in front of a computer all day and just feel like I'm not doing anything active or constructive. Do you feel this way? I walk/jog in the morning--this morning it was only 2, not 3...but I still feel like I'm setting the example for my kids that its OK to be sitting in front of the computer all day. It's over 100 degrees so I can't shove them outside all day, but I have them go out for an hour when it's cooler in the AM and then for 30 minutes in the afternoon. Also, the TV can't be on for more than 2 hours so the have to find constructive things to do. Is this normal? Am I the only one? They go to daycare 2 days a week and are home with dad or I the other 3--I just can't take them to the park or the pool since I am WORKING at home. Ugh. Advice?