Endurance workout:
4*500 rest 40 sec
Rest 3 minutes
4*400 rest 40 sec
Rest 3 minutes
4*300 rest 40 sec
Rest 3 minutes
2*100 rest 40 sec
Total: 5000m
Or
Endurance workout:
4*400 rest 40 sec
Rest 3 minutes
4*300 rest 40 sec
Rest 3 minutes
2*100 rest 40 sec
Total: 3000m