Sometimes an opportunity comes along that you know will challenge and push you forward. It's the next step, and it promises to change you for the better. Maybe it's additional responsibility, a chance to lead, or something more.
But to follow that path means leaving another. The path you've been on, the easier and safe one, it must be let go. You cannot follow both. It's scary, as you'll never see where the path ends, and there may be twists and turns, but it will be worth it.