Years of cycling have developed my legs into tree trunks. I don't do much of anything for my upper body.
One thing I've learned is that diet has a much greater effect on weight gain/loss than exercise for most people. Exercise, and especially exercise performed in the cardio zone, is great for maintaining overall health and keeping blood pressure, lipids, cholesterol, ect. in check.
I say most people, because if you're doing 15-20 hours per week of hard cardio, you can pretty much eat anything you want, but most people aren't going to do this or at least won't maintain that regiment over long periods of time.
If someone is strictly wanting to lose weight, focusing on diet is a great way to go. I've never been much for fad diets. Counting calories by portion control has always worked for me. With the smart phone apps you have today, it makes it really easy. For eating at home, get a kitchen scale and weigh your portions. For eating out, get good at estimating portion sizes and taking doggie bags home. Using these methods you can eat whatever you want, but you find out pretty quickly that lower calorie, high bulk foods fill you up much better than high calorie foods. The hardest part of dieting is the first few weeks. After you get into a routine, your body accepts what it is being given and your hunger levels will go down. You don't want to get too aggressive with dieting. Some people want to lose 10 lbs per week or more, and the problem with that is you're going to be losing a lot of muscle along with the fat doing it that way. As you get older, lean muscle mass gets harder to put on. A slower, long term approach works much better.
Naturally diet combined with exercise is going to produce the best results. For reasonably healthy people, I always recommend cardio exercise because it's much more efficient and produces greater health benefits. Walking, slow biking, etc. is fine for those who can't do cardio, but if you can, cardio is the way to go. Do something that gets your heart rate up. You want to get your heart rate up to the point at which you can just barely carry on a normal conversation, and maintain that rate throughout your routine as much as possible. Heart monitors work very well and are a great tool to use for this. As with diet, the hardest part is getting started. Once you get into a routine it becomes much easier, your muscles don't ache, and you will really start to notice your health and energy levels improve. Start slow with say 15 minutes in the cardio zone or at much as you can do. With each week, try to do a few more minutes. Your endurance will build up pretty quickly.
I also recommend that anyone just beginning a diet and/or exercise routine go to their doctor and get a full physical before they start. Not only is this important for making sure you're healthy enough, but to establish a bench mark so you can guage how much your health improves over time.