It's strange, but the 
It wasn't that it was a great workout; in fact, it was short, as I've been used to lately, and although I ran slowly, I can tell you that I struggled mightily to finish it, and I'm talking about a 5km workout at 5'20"/km pace...
On the other hand, the day was exceptional: 23 degrees, sunny, and a light breeze, but my legs couldn't go any faster after almost two weeks without running and having suffered from the flu for five days...
Well, I'm not complaining. I'll be back to my normal shape soon, no doubt about it, but it really pisses me off that I accidentally lost some of my fitness.
Keep on running! (Always!)
