I used to work 12 hours a day 6 days a week, tried drinking 12 pints of milk a day to gain weight, nothing, not a pound.
2 gallons of milk a day.

How many toilets did you have to replace?
Find a dairy farmer, drink the whole milk you get from them and I guarantee you will bulk up! Not afraid of real unpasteurized milk are you?
I doubt pasteurization would have an effect on calories. On top of which he's full of shit unless the milk replaced, rather than supplemented, his usual calories.
Nutritionally, I think it will destroy some enzymes, such as lactase (which might save him some $ on toilet replacement), but that's more than offset by the fact that pasteurization kills lots of really bad bugs. Tuberculosis is the prime risk with raw milk. It's afficionados and purveyors don't really publicize that. Please ask a doctor if you're a big time raw milk guy.
Agreed
I have a desk job, would rather do this. In my university days I did a couple of temp manual jobs, I would get home shattered with strained joints, my knees definitely did not take kindly to standing up a whole days work, not in the parking lot not in the grocery store not anywhere.
No surprise. They had you sitting at a desk since you were 6yo. I'm sorry to hear you were unable to break free of the cycle.

Don't lose hope. It's never too late get a real man's job.