Leisure is the time for doing something useful. This leisure the diligent person will obtain the lazy one never.

Free hours and idle hours are being separated here. The claim is that time genuinely your own is produced by having got your obligations under control, and that anyone permanently behind never gets any, only guilty gaps between tasks. That distinction is real, though the framing is harder than it needs to be, since plain rest is useful too and does not have to justify itself.

Look at whether your downtime is chosen or merely left over. Getting one recurring obligation properly finished usually converts more anxious gaps into hours you can actually use.