As you play a bit more your stamina will become less of an issue. I'm on about day 20 now and I have eight patches of crops which I am watering every day while still having stamina left to go around town, chop some wood and stone, and forage a bit.
I went and bought the guide for it because of all the tables in there, and one of the things which really is true is that you're going to have trouble farming lots of crops at the beginning, but as you gather more food and upgrade your tools it won't be a problem. I am yet to upgrade my watering can, but I can tell that when I do I'm going to be able to do my entire field.
Tool upgrades are done by sockets. Each tool has one socket to start, and you can buy new tools with more sockets in them. You place gems in the sockets on the tools which allow them to break larger objects, water more, reduce the stamina usage, increase carrying capacity. I'm looking forward to trying this new upgrade system.
As a final note, I'm just about ready to buy a chicken coop, so we'll see how the animal care is in this game soon!