I used to be really overweight and when I was running 12 minute miles on the street desperately trying to shed the pounds and get fit, it used to discourage me a lot when people used to breeze by me.
I am in good shape now and my training pace ranges between 7-9 minute miles and over the last few weeks since there are lots of new overweight runners trying to get in shape because of new year, I found myself overtaking a lot of these people and I feel damn awful about it because I kmow what it was like to BE in that position.