When referring to a difficult task: "That's a tough road to hold", or "a tough road to hoe", or "a tough road to [travel on]" or "a tough road to... [trails off awkwardly...]", or just "a tough road".
It's a tough row to hoe.
It's an agricultural metaphor. The row is a line of dirt in a field where you plant seeds. You use a hoe to dig the lines, remove weeds, and create little holes where you drop the seeds. Hoeing may be difficult if the soil is too hard or too full of rocks and weeds. Such a row would be a tough one to hoe.