Do it in bits. Getting tired, blisters, wounded, makes it all hard, but five minutes, and a tea break, then five minutes, and walk around, and after a while you will be doing ten minute hits, and it adds up. After a month you will be suprised how much you can do, and still feel good.
One trip heavy loaded, you are shot for days, break it into three, and you will get stronger.
There is a line, work harder, get run down, stay on your side. The line keeps moving, you can do more, for longer, and still, keep it in your range. There is a time to work, and a time to sit and look at it.
Slopes build good legs, ask the land what it is doing, you might discover it knows best. Until you have seen it through a season, don't do things that will make puddles. Look at the slope from all angles, level one area, make a cliff in another, and that might get out of hand.
Fencing one acre is work, better a small tight pen, than chasing stock over the countryside. One for a corner brace, then building out, is less work for area enclosed. Digging postholes, or driving metal posts was something I hired out when I was much younger. I will set posts, tampt them in, stringing wire is easy, except carrying it. The wheel barrow is your friend, get one with a big tire, or beter yet, the carts with a heavy bike size tire on each side. They haul tools, materials, and make a handy table and bench.
Don't hurry, don't get mad, and you will get more done, and enjoy the work. You are going to look at it for a long time, and a job well done is a joy to behold. Make yourself happy.
Spread the seed for a good pasture mix before you need it, it takes a few years to establish. It will choke out the weeds and leave a good stand of feed when you do need it, with good roots. It will withstand dry periods, and grazing makes it better.
Ask around, in some places a little lime makes everything better. Hang out at the feed store and talk about the weather. Wear a hat, it makes you look country. Learn about your soil type, the names of good grasses. If you plant field flowers, make sure they are not weeds, that will spread, or toxic to stock. Ask at the feed store, show you are trying to do right.
Not a lot of effort to spread lime and broadcast seed, and in a few years it can make the place look rich. Clover adds nitrogen, alfalfa sends roots deep, good cover enriches the soil, and holds water.
Love your dirt.