The work you need to do to gain muscle mass for example will require consistent and planned weight training. That is physical activity that conditions your body into the desired bodily adaptation. Thinking about growing won’t bring forth the goal, work will.
It’s just about Spring again and you’re ready to lose a few pounds and get back to the fitness level you remember so well, those days when you could run fast enough to catch the next bus stop in no time. That’s all good, the determination is there and you have your gym wear ready but do you know what you want? You can run right now if you had to but do you know specifically what you want to achieve through exercise and a better dietary plan?