Throughout the game you are given stamina points. Each day these points start back at 100%. While playing the game you use up energy by doing actions such as Milking your Cow, Brushing your Animal, Cutting the Grass, Watering your Crops, Planting your Crops, etc. Below is a list of the stages of Stamina, how to watch them, and what to do to recover that stamina.
Wipes Sweat off Forehead
The Hero will do this usually when he is at about 70% of stamina left. This means that he is getting tired but still has enough energy to make it through the rest of the day. If you want you could eat a little something to increase your stamina.
Taking a Breather
When the Hero has about 30% of his stamina left, he will bend over and talk a quick breather. This means that he is starting to become low on energy. You should either eat some food or use the bath in your Kitchen if you have one.
When the Hero has about 5% of his stamina left, he will collapse for just a second. This means that he doesn't have any energy to do anything but walk and sleep. Immediately eat something, drink something, or take a bath in your Kitchen if you have one. Usually you will want to go to bed if he starts to collapse.
Every day you start out with a Red Happy Face (press the start button to see this). After passing through these three energy stages, the face will change in appearance when you press the Start button. Watch the face throughout the day to remind yourself how much energy you have.