If the Christian life is like long distance running

You do improve with practice
Your style and pace are very hard to change
Running when you are older, doesn't look very fancy, but still works.
Knowing the route is helpful.
Looking into the distance, and thinking about how far, how steep or how hard it will be is sometimes discouraging,
 Just sticking to a pace you can maintain, concentrating on, and enjoying what immediately surrounds you and not worrying about others running better than you helps you complete a route.
Trying to interpret a sign from a distance can give the wrong information, better to wait until you are close to it.
Speeding up too soon can wreck things.
Running with someone else can be very helpful, particularly if you care more about the shared experience than the pace.
Running usually hurts, even when you are doing well at it. 
The right clothes, shoes and temperature helps.
Getting through a run is basically between you and your body.
Walking is OK, and sometimes unavoidable.
Stopping is OK, and sometimes unavoidable. But that doesn't mean you can't start again.
Finishing doesn't feel amazing, but it is a great relief.
Running makes you sweat and stink.
There is a wholesome satisfaction once the run is complete.