Whatever you do in terms of exercise and diet, it must be sustainable and flexible.
There is no point in signing up to a gym and crashing it for the first few months before realising the exercise schedule was not practical. Equally, there is no point in crash, or fad, diets, if they are dispensed with after a few months because they are impractical.
The choice of exercise and diet is down to the individual and their circumstances in terms of age, condition, the time available etc. The point is though, whatever you decide on, must be balanced, sustainable, and practical to do.