But it's not a whole lot of effort is what I'm saying, compared with let's say squats or bench presses or whatever. And as for results, even if you can't see a six pack because of a higher body fat, I like the feel of a having a strong core/stomach.

What are your goals and what else are you doing workout-wise? Do you train at home or in a gym?

Working out at home.

Chin-ups 3x of around 8 reps each
Pushups 3x of about 17 reps each
Lat row, generally on the couch with about 25 lbs. each side, 3x 12 reps each
Shoulder press, dumbbells, 3x for 15 - I'm rehabbing a shoulder

Legs is: (2-3 times a week)

Single-lag squats 3x 10 reps
hip flexors to work on runners knee
Glute bridges

1 to 2 times a week with this, and just straight full-body squats 30 reps each, 3 sets on the other days.

In some cases, if one is already doing a lot of heavy compound lifts (squats, deadlifts, overhead presses), additional ab work might be unnecessary but I would say this isn't the case here.

As with all training you should strive for progressive overload when training abs. Don't do a set amount of sets and reps all the time, try to up the weight or the amount of reps every or every other workout, while maintaining good form. Obviously this isn't possible every time but there should be some general progress over time.

I'd recommend staying in moderate rep ranges, somewhere around 10-20 reps. Somehow people think that you should do super high reps for abs but while this absolutely can work, there is a big chance that you will stop a set due to systemic fatigue and not really because you've come close to muscular failure, as you should. Therefore, at least if you're not a total beginner anymore, try more challenging exercises or use added weight.

You also don't need tons of exercises, pick one or two for each muscle group and you'll be fine.

For the rectus abdominus weighted crunches or kneeling cable crunches are pretty good and easy to progress with. You can do the latter with a band attached to a pull-up bar, although I personally don't really like the resistance curve on this one. I prefer the former option. If you stretch out the arms holding the dumbbell above your head (so basically parallel to the floor), you need surprisingly little weight due to the long moment arm.
An ab wheel, while it might seem like some silly gimmick, is also extremely effective and hard, if done correctly. But make sure to watch a video on how to use it, since most people use it incorrectly.

For obliques, if you want to train them, something like wood chops or pallof press is pretty good. Also possible to do with a band, although once again I dislike the resistance curve. Good old side crunches can be pretty good. You can also use weights for those and/or raise one arm up and to the side. You can also do hanging oblique raises which are very challenging but your grip might tire first. Some kind of side bridge variation, possibly with a twist motion, is also a good option.

For lower abs do leg raises, either lying or hanging.

I personally currently do wheel rollouts, side crunches with arm raised up and lying leg raises with a bit of a dragon flag type thing towards the end of the movement.

If you want to save time you might want to do some kind of intensity technique like rest pause, myoreps or even drop sets.
But I wouldn't recommend doing it right away. When you don't have much experiece with training or even just with an exercise, you might gauge reps in reserve incorrectly. There is also a bigger risk of form breakdown with intensity techniques and this might be detrimental for your spine with some types of core exercises.

Does anyone have any tips on how to get out of a no exercise rut?

I had to take time off due to a chest infection, then I was isolating with covid, then my boyfriend got his genetic testing results which wasn’t the best news and I’m really struggling to get back in to it.

I like a huge variety of exercise but anything I try right now I just cba. I’m not sure if I should try and force myself to continue and I’ll end up getting back in to the swing of things or if that will make me hate it.

Have you tried hopping some fences at the zoo? Lots of motivation for exercise.

I’m too fat to run

I think most people will just advise you to make a decision and stick with it. Once you start exercising, even on days you really don't feel like it, eventually you get into it.

Yeah I am going to give it a go. I ended up going a walk last night and felt 100x better after it, it seems to be getting myself up and out the door that is the main struggle.