I like doing this:
Monday:
2x5K keep getting faster over time
Wed:
30 mins with heart rate between 130-140 (adjust your hr as needed. Should feel too easy. )
Fri:
500m sprints...maybe 4. Maybe PR a 500 once every 2-4 weeks.
^ it's like a weird conditioning version of daily undulating periodization (fuck, how I hate typing out that pretentious phrase).