It's important to exercise regularly. If you set a schedule, stick to it.

[ He might sounds like he knows stuff but... he just researched the basics when Sheryl asked him to help, really. ]

Getting good eating habits helps enormously, but it also depends what you want to achieve. If it's just "keeping in shape" it's going to be a lot less intense than "I want to get stronger/faster" or "I want to lose weight".