Because you're going to run into real tough times.
English phrasal verb
run into
To meet or face something unexpectedly.
Examples from real speeches
See how speakers use “run into” naturally, then open the full speech for more context.
And I've also run into stubborn mental barriers that made me want to bang my metaphorical head against their metaphorical walls.
As she ran into the arms of her family and they celebrated a joyful reunion, my father got very quiet.
And countless of women and men, mostly women, run into it in their professional and personal lives, and I'm sure a lot of you can vouch for that right now.
So armed with all that wonderful material, those great ideas, I ran into my publisher's office and I told him.
Then, a year ago, we ran into each other again.
And I still don't know why the desired effect of running into my arms in slow motion was replaced with a screaming drama in which she flew up the stairs screaming, "Amma, come here.