Swim 20-30 minutes using pull buoys to eliminate lower body work. Focus on your technique, especially 1) posture (nose pointing down), 2) direction (extended arm points straight ahead--not across the centerline), 3) length (looong reach), and 4) catch (fingers point _down_ as hand enters water--_not_ at wall).
Ride on a mostly flat course or indoor trainer staying only in heart rate or power zone 1. Cadence should be comfortable. If it begins to feel like you are working at a harder effort than z1 normally produces, stop the workout and stretch. That's all today. Otherwise, rest and recover. Stretch after.
Swim about 40 minutes (less is also OK). Work only on technique (posture, distance, length, catch) by swimming _only_ 25s. Each of these is done at about Olympic-distance effort. Recover for as long as you want. Do NOT time the 25s or the recoveries. This is NOT a workout. It's all about recovery.
Run easily on a flat course or treadmill for about 30 minutes. Stay only in heart rate or pace zone 1. Focus on relaxation, especially of your face and hands. This will help to relax your entire body. Feel free to shorten this run if the effort feels high. Stretch gently afterwards.
Ride easily for 1.5 hours on a mostly flat course or indoor trainer in zone 1 heart rate or power. Keep it easy. Your cadence should be comfortably high. Pay attention to your intensity. Easy! Stretch after.
If you generally swim with a masters group this is the first day to consider returning to their session again. If you do, consider shortening the workout or taking more time to recover between intervals--especially if you still have lingering fatigue. Tell the masters coach before the workout of your possible need for more recover. Should you decide to swim by yourself today, repeat Wednesday's swim session.
Run about 45 minutes easy. (It's ok to make it shorter if that seems like too much.) Run only in HR or pace zone 1. Soft surface such as grass, dirt, track or treadmill is best. Focus on a flat foot placement.