Alternate Ks and Mixed Ks

Three of the four seminars for school teachers were over.
I wanted to refresh myself before the last one that's scheduled for Thursday,
so I decided to go for a quick run.
I am planning to go for a 30 K run this coming Sunday,
so I didn't want to tire myself too much.
From among a number of training choices
I chose alternate Ks because it is the least stressful one.
I started by warming up with a short jog for about five minutes.
I then went for my first K at my marathon pace of 5:20/K.
After than I rested for 30 seconds before going for my next K,
which was run at my half marathon pace of 4:40/K.
When this was over, I had a choice between carrying on with alternate Ks
and raising the pace to turn the training from alternate Ks to mixed Ks.
I decided to continue with the former because I didn't feel strong enough.
When I was done with 4 K, I had the same choice again.
But this time instead of repeating alternate Ks,
I wrapped up the training by raising the pace to my 10 K pace of 4:30/K
for my 5th K.
When it was over, I was completely done.
I took a two-minute rest and slowly jogged back home.
I am going to give myself a full rest for three days until Sunday
when I am going to run 30 K.