I know it's lazy to just post a video. I did read it. But this is a good video that I think would really help you out.
If you wanted for example the simplest way to instantly make this more interesting, just have your main character do one thing that is unexpected and unexplained. You don't even have to write the payoff or reveal yet. Just do something to cause the audience to begin waiting for a future resolve. In example, when Johnny visit's Claire's apartment to paint, he could use the bathroom and hide a gun behind the toilet. That would keep people reading for 10 more pages. Or he watches Ryan walk away, and the moment he is out of sight, he runs back inside and throws a bunch of money into the bathtub and sets it on fire. Obviously the details would be different in each genre, but the core psychology of what you need to be doing is similar.
I'd add that modern audiences are fairly unforgiving about pacing problems. You don't need to go overboard and do some flash forward to a hostage situation, that's the kind of hamhanded approach you see sometimes, but you do need to start putting in little hooks as early as possible, like kindling, to keep the flame, the attention, going long enough to develop into a fire.