Of course productivity is important, but it isn't an end in itself. Neither are high incomes or appearences of success. If you are lonely and have to sacrifice your health you really have to start thinking about what it is all for.
I agree completely, I'm cautious about physical health now and doesn't trade it for anything. But, that has resulted in me having very little time for productive work and hence I'm in a situation where I need to optimise every bit for it.
