I've recently been making a big effort to "warm down" lately, particularly in running and cycle commuting. My cycle commute/lunchtime run route ends on a bit of a hill and I had a habit of going hell for leather all the way to work and up the last hill and stopping right at the the top (security gate), I was forever getting stiff legs either in the afternoon which was a pain (literally) on the ride home, or just walking around after a run.

I now make a point of continuing running gently down a side road for a bit or spinning my legs easily round and round the the car park (get some funny looks though) before locking the bike up and the difference to my legs has been immense. I also have a recovery drink after the home leg of my cycle commute (at least 40 mile round trip at the moment, more if the weathers good - like today ). If I forget to drink it I really notice it in my heavy legs the next day.

I'd also second the advice about trying to take it easy sometimes, I'm like you and always like to cane it however I've been making an effort on my Friday cycle commute to just go easy and it feels good. It helps that you can go at a reasonable pace on a road bike without masses of effort (unlike my winter hack mtb). I really enjoy it now because its such a contrast to my Tuesday commute and my MTBing (my main thing), I get a good dose of fresh air without feeling like I've flogged myself.