My wife & girls subscribe to a fitness couple's YouTube channel, some of the videos offer real good advice. Eating a healthy diet to fuel an active lifestyle is most important.You need to move the biggest muscles in the body, this means your back, ass and leg muscles.
This is why lifting is effective. I do not recommend investing too much work into ab exercises as they get used enough in other ones, but don't leave them out either.
SQUATS are the most effective exercise anyone can do anywhere:
Speed is not the key to squats, focus on proper form and do it as slow as you can.
Good weight lifting form/technique will help prevent injury, yield measurable results within 4-6 weeks & that's going to sustain the motivation which leads to a healthy lifestyle change rather than exercising with weights for a month before quitting due to discouragement.