If the shoes get old, then he will need new ones...

If he keeps running more, then the shoes will get old

If he wants to run, then he will keep running more

If he wants to do something, then he will want to run

If he gets bored, then he will want to do something

If he needs to wait, then he will get bored

If they need to dry, then he will need to wait

If he washes them, then they will need to dry

If they get dirty, then he will need to wash them

If he keeps running in them, then they will get dirty

If he decides he likes them, then he will keep running in them

If he runs in them, then he will decide if he likes them

If he ties them, then he will run in them

If he puts them on, then he will tie them

If you give a runner shoes, then he will put them on

 If you give a runner shoes