Work on speed. Know that every day might not be your fastest. But every day will bring unexpected surprises that will leave you awe-stricken. When you're halfway through an hour run and you feel like lengthening your stride, giving it just a bit too much effort, do it. Feel the slight twinge of doubt in your ability to make it at that pace. You can always slow down; this is just a training run. But you don't. You persist, you focus, you feel the doubt fade away.
Be tough with yourself. Don't let yourself slacken pace. Fight into the wind and rain. Lift your head and approach sprint level when the bemused commuter glances at you. Wink. Feel the blood pumping through your veins, feel the tension and fatigue in your muscles, enjoy every bit of it.
Because it won't last forever. Channel the stress into physical exertion. Work it to the limit. There is no tomorrow, there was no yesterday. Until the end of the run, when you can forget the whole thing. There is no stress.