+1 with Cougie & 80s MR, all you need is a windproof gilet, Decathlon used to do one with a mesh back, cost about 20quid, I think, or you can always go to NikeTown and pay 165 for the same thing(those swooshes do not come cheap)
ps. and no runner since that Aussie 400M girl wears a hood to run in!!!!
Yes, you can do it, its only another run, just a bit longer, but...... with kids age 3 & 1, unless you get a running buggie with a ski -board thingie for the 3 year old, your'e not going to see them that much if you start real marathon training.
So, don't give up, you can still do half marathons every weekend if you want, and it's a nice day out for the kids, but the training is just not as time consuming.
Once they're a bit older, go for it, and, assuming you're no older than 30something, you've got years and years to do as many as you like (says a 68year old, 2 marathons a year runner)