Just as there are dozens (hundreds? thousands?) of different investment philosophies and investment strategies, there are just as many exercise philosophies. Weight training, cardio, aerobics, cycling, circuit training, HIIT, yoga, etc. The good news is that they can all work, just as various investment strategies can be successful. Some people like certain programs better than others and that's fine. You'll tend to stick with an exercise program you enjoy and get better results than from one you dislike and don't follow. Find something you like to do and just do it. 

If you're new to the exercise world, hire a personal trainer. Someone who can show you the basics and get you started on some sort of program. Then check in with them from time to time as you progress.

The basics of exercise...

Move. Get up and move

Do something that burns calories

Do something that makes your muscles stronger

Do something to stretch