in (something) for the long haul

Dedicated to doing something for a long period of time. This phrase usually describes one's commitment to someone or something. Jill knows that obtaining a PhD is going to be tough, but she said she's in it for the long haul. Once we sign this agreement, we'll be beyond the point of no return. We're in this for the long haul after that. I love you, and I'm not going anywhere. I'm in this for the long haul.