I aim for a minimum of 30 minutes of cardio at least five days a week, via a brisk walk with some occasional jogging. (I primarily use somewhat hilly trails and I jog downhill.) Though I track distance in my journal, it doesn't guide my workout. Instead, time determines it, and from there my goal is to keep my heart rate between 70%-80% of max. That's a nice comfortable pace that burns calories and builds endurance but doesn't get me winded. I use an exercise heart rate monitor, so I can continually adjust my pace as needed.
Weight training is also good, though less important for weight loss than aerobic work. I'll admit I'm not doing any at the moment for a variety of reasons (some are legit and others are excuses
). I was working with a trainer a few years ago who had me on a 3-day-a-week regimen.