I love the midpoint of novels. I tend to be a proactive person. It is like Midpoints were made for me.
On the outside, the Midpoint can be new information and/or a confrontation. It is the second-most tense time in your story.
But what I love most is the inside of the Midpoint.
The characters have been reacting to their circumstances. During the Midpoint (sometimes in the reaction section) the characters transform from reactive to proactive. Because readers see partly through the character’s eyes (but also through the narrator’s voice), the reader’s perceptions also transform.
For the joyful adventurer, the Midpoint is usually some kind of revelation. “Oh no, Voldemort is after the Sorcerer’s Stone, guys. We have to protect it!” Tension here may come from rapid revelations, prophecies, or a string of clues unraveled.
For the reluctant adventurer, the Midpoint is usually a face-off against a bad guy – maybe the main antagonist or his stand-in. This is especially the case when the character is so unwilling that it takes an immediate life-or-death situation (with the threat of a future one) to get the character to become proactive about her situation.
The Midpoint usually comes halfway through the middle. Sometimes it happens sooner but rarely later because readers love excitement. So give them what they want.