Think of the plantar fascia as a rubber band along the bottom of your foot. When it gets overstretched or angry, it screams at you—especially first thing in the morning. Running in flat shoes is like asking that rubber band to do a split.
You need shoes that support your arch and cushion your heel like a tiny pillow fort. Luckily, there are some rockstars in the running-shoe world that specialize in exactly that.