The way to structure a small quality day [red dots are road crossings; used as convenient places to change effort if possible].
A mile and a quarter of gradually increasing speed as a general warm up. Then three quarters of a mile of still gradually increasing speed but as a more specific warm up consisting of 25 metre pick ups followed by 50 metre relaxes [about ten lots of these]. A mile at a relaxed gradually decreasing pace as recovery. Then the main aim of the session, a quality 800 metre effort gradually increasing to maximum pace. A very short, get your breath back, jogged recovery followed by about half a mile of gradually decreasing pace cool down.
To note, the pace at the very end of the run was the same as at the very beginning of the run. Also the warm up [both general and specific] was much longer than the cool down [about four times as long]. The quality part of the session was only 800 metres [an eighth of the total distance] or about 1Km if you include the ten faster pickups of 25 metres each [a seventh of the total distance].
It is obvious therefore that introducing a small about of quality into any run is not really that difficult. One run with an 800 metre effort once a week is not going to be very tiring but will yield surprisingly beneficial results.
Day24 OMC 94 miles