Using the template of R27, now add 10 minutes to run near the end of the route, preferably involving a nasty climb. So, your five minutes from your usual finish, run in a different direction for five minutes out and then five minute back and then continue.
I didn't get the nasty climb in. There were plenty in the begining. First 1.5 miles was 10:18, finisher of 3.06 was 21:36, so I went on until 31:26 and got 4.25 miles in. Felt pretty toasty.
5X100m sprints, rest :30 after each sprint, 8X50m sprints, rest :15 after each sprint.
Swam these without a fins but in a mask. The mask makes me hypoxic. My form was poor on this and I'm not sure if I should really go for form and stop trying to race. I haven't yet because I am SO slow.
weighted pull-ups, 65# 2X10
weighted dips, 65# 2X10
Started these with #65 hanging from my waist. My tender areas were under dire threat. I put on the 20# vest and hung the 45#. It worked well. I rested 1:30 between sets.