As Lukas said, physical work and fitness are very different. Physical work by itself cannot substitute fitness. I am not really good at explaining, I am also an open water swimmer, so let me give a try.
Basically, in every movement, there are the main group of muscles that do the work, and there are other muscles that keep them in check. Your biceps might be doing the work, but it doesn't mean your back muscles are sitting and waiting for their turn. If they are weak, you will have problems (your posture won't be right, more strain on some joints, etc). There are also many smaller muscles that keep bigger muscles and joints hold their shape during and after activity. They stabilize the whole system. If they are weak, you can easily hurt your shoulders, back or knees. So you really need a balanced physical activity to keep each one of them in check. Physical work doesn't give you that. Let's assume you are going to use broadfork or pickaxe. Same activity over and over again. You will burn some calories for sure, but it has a potential for back pain, hernia, shoulder pain and such. That would be my main concern. Increasing your aerobic capacity is sure helpful because it will also increase your psychological threshold, but that will not be my very first focus.
The web (youtube, Instagram, etc) are full of many, many and many wrong -just plain wrong- recommendations and videoes. It is pain to find a useful, reliable and preferably free resource. I can recommend Darebee.com webpage
. There are many programmes over there, which are targeting various fitness levels all programmes
. Download the pdf, print them out, and stick with the plan. It is all free, they accept donations though. They also have a youtube channel where you can watch and learn how certain movements are done.
I would recommend to begin with baseline programme webpage-baseline-program
. Follow it with totals webpage-totals-program
. If you want to lose weight cardio trim is a good one webpage-cardio-trim
. If you feel good enough, try to follow two programmes, such as totals+cardio trim. If you get over certain weaknesses or you want extra-challenges, there are challenges to follow webpage-challanges
. Don't do solely challenges though, you want to keep the balance.
I have to disagree with James about indoor rowing. Even though it is good and very beneficial; if your posture is wrong, you can mess things up badly. Water-rowers are expensive also. I hurt myself with other types of rowers in the past, so I would not even consider magnetic, hydraulic rowers. Rowers are hard on shoulders and lower back (you won't realize it at first), I don't think they are the best for the beginner or even intermediate levels.
I recommend jump-rope. It is cheap, you can do it anywhere you want, and will shed a lot of fat and, well, works the whole body. I would start with 30 jumping jacks and go up to 100 non-stop. Following a week of break, I would start jump-rope. 50 times is a good start. After 3 months, you can either jump for 200-250 times and have a break (walk for 2-3 minutes) and repeat 3-4 times or jump rope fast for 1 minute, have a break for 1 minute and repeat 1+1 for 4-5 (or 10) times. In 6 months you will be able to follow guys at youtube (jump rope dudes and such). Posture is very important. A lightweight jump rope will focus on the lower body, heavier ropes will focus on the upper body.
Try to do exercise 3-4 times a week at first. Don't overdo it. Also, remember that you do not need to eat extra for this level of exercise. You will feel hungry, but that is your body tricking you to eat. You can increase your protein intake a bit (1-2 eggs more). Include bone-broth (collagen type 1-2-3) in your diet (for your tendons). Try to build a baseline muscle tone in the first year and then work on it.
Hope it helps!
Edit: Forgot to say, yeah I do! Do it!