low on energy

I seem to be having a hard time getting over this dumb cold - I'm looking forward to the day I wake up and have energy. With that said I swam 2200 yrds today and 30 min on the stairmill.
First the swim - warm up 200
drills 100
4 x 50 easy
3 x 100 moderate
2 x 150 moderate
1 x 200 moderate
2 x 150 moderate
3 x 100 moderate
4 x 50 - sprint 25 recover 25
cool down 100
total 2200 yrds total time 63 min
I really focused on consistent pace - 60 second per 50 yrds and maintaining good form even when I got tired. Generally I felt pretty good - no sinking feeling. Since I did not have a ton of energy I kept things pretty easy hence the slower pace but I kept the rest times pretty short - max 30 seconds and 15 or so between sets. I also worked on breathing less - I kept it between 3-5 per 25 yrds - even on the longer sets. I also did a few flip turns - the pool was a bit crowed and I'm still learning..
After I swam I did 30 min on the stairmill which I felt I needed to do since I have to coach skiing this weekend and who knows if I will have the energy to do any workouts after a day on the hill freezing.