FIrst of all, congratulations on taking huge steps to gain control of your health.
A few items:
It is vital that you incorporate resistance/weight bearing training in your workouts, here is why.
Imagine you have 2 items, let's say hamburgers

in front of you, and they look and weigh exactly the same.
But... when you cut one down the middle it is full of awful fatty meat, yet the other one is full of organic, extra lean ground beef.
Does the actual "weight" matter? No. The content does.
My point:
Lean tissue mass (muscle) burns fat. In some cases, the scale may go up a little, but your body tightens.
Saggy skin is a result of rapid weight loss, usually through cardio.
Cardio is just one component of overall healthy weight loss, but ut cannot build lean tissue, only weight bearing activities can do that, and it is that, which tightens the body,
A thousand crunches, no matter what variety they are will not burn an ounce of fat, I know! Isn't that awful? lol Unless you have a very strong core, I would advise against sit ups as it will be your lower back that winds up doing most of the work.
Also, spot reduction is not possible, you cannot lose weight in one part of your body, any more than we deflate just one part of a tire.
The way I lost the 160 Lb was slow, but it has been off for ten years. More importantly, my body fat was at 48.9% and I reduced it by over half, but not with cardio only. I focused more on resistance exercise and cross training and added cardio. I moved my carbs to more of the complex type and consumed these earlier in the day. The biggest factor was acquiring knowledge about what I was eating, that made all the difference in the world. Everyone is different, but that is what generally seems to work at least with the people I have worked with.
Thank you for taking the time to answer my first question.
Please feel free to write again. I hope this was helpful in some way,
KEEP GOING STRONG!!