While there are many excellent ideas to think about in the responses on this thread, already, I would like to register my opinion that there is no "one-size-fits-all" regimen, or type of work-out, that's "best" for people of all ages, all physical conditions, all body-types (by "body-type" I mean such genetic factors as metabolism, and your tendency to have a "natural" gene determined optimal weight).
Also, your long-term, and recent, exercise history comes into play here: it's one thing to be re-starting to exercise after a long period of not exercising; quite another to be very obese and just starting to exercise; another "universe" entirely to be over sixty, and start weight-lifting.
Without knowing the details of your age, your current physical condition, your history of exercise, and more information about your diet, metabolism, sleep habits, use or non-use of stimulants, tobacco, alcohol, etc., I don't think a lot can be said, except to congratulate you for starting to exercise !
But, one generalization I think can be made is that working out ... doing the same work-out ... more than four or five times per week is probably too much. And, particularly if you are "pushing your limits" you need to consider, and find, your body's minimal rest period for restoration.
On the other hand, if you are varying types of exercise, for example: doing cardio three times per week; doing weights twice a week; and swimming twice a week, imho, I think that can be a good thing.
The key thing is to avoid resuming exercise to fast, and too intensely, after a period of relatively not exercising. To do that is to risk injury, and the kind of exhaustion that will lead you to stop exercising, particularly: imho, if you are over fifty years of age.
A key variable you can work with, as referred to in several responses here, is "intensity:" as you probably already know, achieving a certain level of intensity, and maintaining it for a certain amount of time, is essential to increasing "aerobic fitness."
Similarly, the relatively newer concept of high-intensity interval-training (HIIT) in anaerobic exercise, suggests that short intense heavyweight work-outs, interspersed with exercise using lighter weights, can give you quicker gains in strength, and stamina (I have not seen studies of anaerobic HIIT and weight loss, or gain).
Finally, there's every indication that using "variety" in your work-outs, varying their type, and what you do, has a strong effect on total impact and carry-over of strength and fitness into everyday life.
For me (age 69), a combination of alternate days of aerobic exercise, and weights, with two days off, and then a swim-day, works best, but I vary that by sometimes doing a work-out where I alternate fifteen minutes on a treadmill with a circuit of several weight-machine exercises where I do high reps per set, and repeat that cycle three times.
The more you exercise and observe carefully how your body responds; the more you pay attention to your diet, and adapt to a more healthy way of eating, the easier it gets.
My own personal bias is that a longer-term effort involving exercise and slow change of diet is much better than any "dieting," per se. And, for some people, like myself, born with a very slow metabolism, and a large frame, we need to accept that being large (not obese, but heavy, and having more body-fat than other people) is just a natural part of who we are.
good luck, Bill