To heal stamina and fatigue, you have a few options:
1.) Go to Hot Spring (unless you have your house upgraded, which in that case...)
2.) Bath in your house
3.)Turbojolt or Bodigizer
4.) Once you've gathered enough grasses, you'll get a message in the mail from the Hospital saying that they have Turbojolt and Bodigizer XL, which are better versions of regular Turbojolt and Bodigizer
5.) Elli Leaves, which I'm pretty sure heals all stamina and fatigue
The recipe is: 6 types of burnt food (use different utensils), Bodigizer XL, Turbojolt XL, and then the utensils are the knife, frying pan, oven, pot, sugar, salt, vinegar, miso, soy sauce.
Also, if you don't know how to eat the food, take it out of your rucksack and press 'B'. And another food that heals some fatigue is honey, but it doesn't help much.