Why not? Exercise doesn't mean going to a gym. Exercising should be fun. You should find something that you love. Get your heart rate up, sweat a little, evaluate how you feel. I almost promise that after you exercise, you will feel incredible. And if you don't? You won't.
I skipped my workout on Thursday. I had a very stressful day which completely killed my energy. I was almost falling asleep on my drive home at 4:30. I should have gone to the gym. I should have driven the 3 miles and at least sat on the stationary bike and peddled for a bit. But I didn't. I stayed home. I ate dinner, took out the garbage and watched Project Runway. That habit is breaking and it will be 100 times harder to go today but I must.
Because no one ever regretted working out.