I believe that co-creation and destiny are the same thing. You are CO-CREATING with destiny. Learning the full manifestation process in The Formula & Magnetism Workshop, you learn that The Universe's only intention is to guide us back into our whole, authentic, most powerful version of self. All of the work I teach is about cracking down your ego shell and questioning and deprogramming societal programming so that you can step into your authentic powerful self. The self you came onto the planet as. The self (soul) that chose this body to carry out your destiny. That is magnetism. When you are in that state and aligned with it, destiny is moving you at your divine current (manifesting), and you are asking for what is in alignment with your destiny naturally.
Meaning, that when you align deeper with that state, you are asking for heart-centered wants that are equal to your authentic needs. And because you're in your authentic worth and expansion about it, they tend to align very easily. However, the further you are away from your authentic wholeness, the more that you will receive lessons and tests that come to literally earthquake you back into your authentic state. The more tests that you don't pass, the bigger the lessons become and they usually tend to come through the life avenues that matter the most to you.
Example, say that a client is obsessed with finding a partner to complete them. They aren't in their authentic worth and they chase after the old dysfunctional modeling that they picked up in childhood - the emotionally unavailable partner - each new person that shows up will tend to create deeper heartbreak (or ego dismantling). Why? Because this person cares most about love and the way that they will learn quickest is through the thing that matters most to them. It's all an act to shatter one's ego to get them closer to their totally whole and authentic, powerful selves. For another that lives in severe lack, their lessons might come in forms that jeopardize their financial security. You get the point.
I can say this from personal experience, and through watching clients evolve and unfold.
"Life just happens" when we are further away from our authentic selves, and when we're manifesting out of ego (and I'm very lenient of what ego means which you learn in F&M). It's all destiny. However, the more we UNBLOCK and align with our authentic selves, expand, and don't settle, "manifestations just happen."