Aside from your mental state, which is entirely within your capacity to control, there are two other items that you can fully regulate most of the time as well: your diet and the amount of rest you obtain. Both are as essential in building strength and size as is exercise.
Strength is built on solid foods. Meat, fish, poultry and eggs. Milk and cheese. Thick hearty soups. Whole grain bread. Fruits and vegetables. All sorts of nuts, beans, peas. That’s good eating. That’swhat you need to build strong, solid, healthy muscles! Two nice-sized meals a day are usually enough for most mature people who train. Many people can easily do with three big meals a day, plus one or two healthy snacks if they train hard and try to couple it with a full-time job and family responsibilities.