Well if you can for example spend 4 or 5 hours in the garage block sanding and your body doesn't ache too bad you're lucky, for me I don't feel it till hours later. I realize i may be out of shape too though. I mean I can still do it it hurts more than 30 years ago LOL I also don't do much during the week 25 years ago I'd spend 2 to 4 nights a week after work in the garage till 10 o'clock at night...that slows me down a bit.
