[wakawaka28]

I think your dad's experience is in the minority. You could usually do that kind of work until at least your 50s. What people in his position often do is take office jobs in adjacent fields. For example, if you were a mechanic but can't work that anymore, you could work in customer service or sales since you know something about the business. If you really stick it out till your 40s and beyond, management or entrepreneurship might be more appropriate. But that isn't for everyone.