It's important to note that fitness is not really a project with a beginning and an end - it's a journey that you will be on for as long as you live, basically. As such, you ideally want to find things that:

• Can sustainably fit into your life
• You truly find joy in doing

For example, I used to think that the only viable form of cardio was running, and that I needed to be running for the sake of my health. The problem is that I fucking hate running, I consider it to be boring as shit. Hence it was always an uphill battle to run for me.

In its place, I've found cycling to be an endless source of fun - I don't really have to try hard to go cycling, because I yearn to do it as much as I can reasonably fit in.

So I recommend that you try different things until you find something that you really enjoy.

Other than cycling, I really like strength exercise. I used to have easy access to a gym earlier in my life, which is unfortunately not true where I live today, so to get strength work done, I do a routine of body weight exercises. This is by no means the perfect way to become stronger, but you really shouldn't let perfect be the enemy of good. The best fitness activities are the ones that you can consistently do indefinitely.

Finally, two things that caused problems for me at the start of my fitness journey:

Having neglected strength work for all my life gave me some muscle imbalances that didn't correct themselves by just doing regular workouts, I had to consult with a physical therapist to learn how to counteract these years of inactivity. The same may or may not be true for you.

Being overweight posed a big challenge at the start of my fitness journey - higher-intensity exercises can really hurt when your organs are a bit cramped by fat. After a huge struggle with dropping my weight, I noticed that a lot of exercises that previously hurt a lot no longer do. This may or may not be applicable for you either.