Ok, let's go over some basics. What people describe as "being fit" or "getting in shape" is really just the the body's adaptations to exercise or diet. These adaptations may include increased muscle-mass, loss of body fat, increased bone density, increased cardiovascular/respitory endurance, increased stamina, more strength, and so on. However, the key thing to understand is that the adaptations will match
exactly & specifically the stimulus the body is presented with.
What that really means is that if you do "light" exercise - such as long, slow distance (LSD) walking, jogging, biking, etc (aka "cardio") - your body will make "light" adaptations. The only stimuli that LSD cardio really presents are the need for your body to deliver oxygen and energy to your muscles (usually just the legs) while in the oxidative (aka aerobic) metabolic pathway. Therefore, the primary adaptations that your body will make are those that increase stamina and cardiovascular endurance in the oxidative metabolic pathway. This form of cardio can also burn a decent amount of calories, which your body will respond to by burning up
mass (see below). Finally, cardio is relatively easy to learn and low intensity enough that even the most out of shape people can do at least a little.
Now, obviously, all of the above points are beneficial for overall health and athletic performance. However, consider what's missing: training using LSD cardio alone neglects or even leads to decreases in strength, speed, flexibility, power, bone density and even muscle mass (weight lost during cardio consists of not just fat, but muscle too). It also completely ignores all the energy pathways besides the oxidative ones, including phosphagen and and glycolitic, both if which are important for health & performance. Finally, it often only trains a few parts of the body (the legs) while ignoring the rest and workouts typically take a very long time.
This makes LSD cardio an especially dubious choice when considering the alternative: anaerobic training. This includes weight training, gymnastics, plyometrics, and interval training, all of which present a wide variety of stimuli to the body, leading to numerous adaptations which improve strength, power, flexibility, speed, muscle-mass, coordination and so on. Anaerobic training also burns plenty of calories and is essential in maintaining muscle-mass, meaning that the weight lost will be primarily fat. Anaerobic training can also lead to increases in muscle-mass and the "afterburner effect", both of which effectively boost metabolism. Moreover, and this is essential to understand,
properly structured anaerobic activity can lead to MASSIVE improvements in aerobic fitness (including stamina & endurance in the oxidative pathway) that typically rival and beat what you can achieve with just LSD cardio. Anyone who has done Tabata intervals, the CF workout "Fran", or 20 rep squats should know exactly what I mean.
In short, anaerobic training lets you achieve all the same goals that "cardio" does, usually in a shorter time and more effectively. It also provides numerous training adaptations that LSD cardio doesn't which are essential whether your goal is weight loss, athletic performance, or overall health. It's certainly not the only choice, but as we all have a finite time in which to exercise, it's probably one of the most effective ones. Of course, one big caveat should be mentioned: no matter what routine you do, diet is going to be an essential component. For more reading on all of this, make sure you read the excellent
"What is Fitness?" article.
With all that in mind, a good strength training routine such as Stronglifts or Starting Strength are excellent choices. For overall fitness & health, an even better choice would be
Crossfit. Yes, CF may seem extremely hardcore and difficult, but as explained in
"What is Crossfit?":
The CrossFit program is designed for universal scalability making it the perfect application for any committed individual regardless of experience. We?ve used our same routines for elderly individuals with heart disease and cage fighters one month out from televised bouts. We scale load and intensity; we don?t change programs.
The needs of Olympic athletes and our grandparents differ by degree not kind. Our terrorist hunters, skiers, mountain bike riders and housewives have found their best fitness from the same regimen.
Of course, to do CF properly, you need access to the proper equipment, which typically means a gym membership. What is this traumatic gym experience she had that prevents her from going? I don't mean to sound like an ass, but it really just sounds like an excuse. Even so, if you really can't get access to any equipment,
here is a PDF of CF workouts that use bodyweight or minimal equipment.