Hi @Nyx!
Congrats on taking steps towards fitness!
I am currently in a high fitness phase (triathlete), but I have been in the same boat many times in the past. Usually, it's when there are too many competing interests/priorities, which makes it easy to fall off the fitness wagon. I firmly believe in taking small steps to gain consistency (frequency), and then grow it (duration) sloooowly from there once it is a habit. Too many people take far too big of a step and absolutely hate it, and then end up reverting back to old behaviors. Eg. "New Year's resolution" folks at the gym going gangbusters in January but who are gone by February.
Good news is, fitness is totally doable! You mention you have a gym membership? If it isn't too far away (say, within a mile or two), one good way to do it is to walk/run to the gym (cardio). If it's farther, can ride a bike. If nearer, can take the scenic route. Then do a quick 15 minutes of nonstop circuit training (muscle and cardio) and walk/run back home. Done in less than an hour, 2 birds 1 stone on the cardio, weights. 3 or 4 times per week to start. It's perfectly fine to start with walking and a few steps of jogging here and there. With consistency, it's really remarkable how quickly fitness can come, which feels great and enables more running and time on the weights! Anyhoo, just an idea/example. So many ways to do it!
I dislike following specific dietary restrictions, but I do believe in limiting calories to maintain a small deficit. There are apps like MyFitnessPal that can help with this, as I'm sure you've heard about.
I wish you and others well on your journey! Moderate to high fitness feels super good, and is so worth the effort, IMHO. (I'm a cardio junkie now, but was into weights in my younger years.)