3 x 6 min with Level Change

Vary stroke rate as follows per interval: 

First and second intervals: 

2 minutes @ r20

1 minute @ r24

2 minutes @ r22

1 minute @ r26

Third interval: 

1 minute @ r20

2 minutes @ r24

1 minute @ r22

2 minutes @ r26

Let the rate control your speed while staying consistent with each interval.