A layoff, death in the family, a violent assault—in 1999, the hits just kept coming for Antoine Craigwell, then a young adult trying to make his way in New York City.

And so, one November day, he inched toward the edge of a Manhattan subway platform and prepared to take matters into his own hands: He would jump in front of the oncoming No. 1 train and end it all.He steeled his nerves—then he thought of his family, including his adopted mother, who’d buried his sister just months before. Craigwell backed off.