Another thing that was making it hard for me to meditate longer than 5 minutes was a physical inconvenience and the thought: "I don't want to do it any longer, I just want to stop". Then I started to just note this thoughts and sensations, without getting attached to them, just stating the fact: "my back hurts" or "I feel the desire to stop the practice". Just note it, admit that you have those feelings, don't try to suppress them, but not dive into them, observe from the distance.
Summing up, it's important to view the meditation as an active process: as training or exercising. It's not daydreaming. We train our minds and bodies not only to focus on the present moment but also fight a bad habit of instant gratification. In this sense, the less you want to continue meditation, and the more thoughts and feelings try to make you stop, the better – because then it's a real challenge, which means the exercise will be effective. Hope that my experience can be useful.
Good luck with your practice!
You might think, "oh but that's not _real_ meditation", to that I say you aren't born Olympic running champion, you first have to learn to walk, when it becomes obvious how to do so, the next step isn't so daunting, and the next, and the next,…
Have fun ☺️