Training this winter

Yeah but...

It's still a commute. Chances are you'll burn out (slowly over time) whilst getting very few gains. Why not keep the commute strictly for easy or recovery miles?

Well, by now everyone knows what I think about exerting yourself during commutes (it's rubbish), so I'll move along...

Completely agree with BMMF, reading some of these posts though[t] makes me think people do over exert themselves on the ride into work?!