Not Sure How I Feel

i have been reading the book "Chimarathon". it is about running better for your body, to simplify. the author is a strong prponent of not exerting yourself above your max heart rate. well, mine is 155 and normally my heart rate is around 170 when i run. so, other than focus on the correct techniques i also had to try and keep my heart rate around 155. he also recommends breathing through your nose, figured i would try that as well. i was able to keep my heart rate at 154 as an average for the run, however, i had to go really slow. maybe my heart is not in very good condition right now but my pace was over 11 min/mile. the 2 other runs i have had recently had been under 10 min/mile. on the positive side, i felt like i could run 4 more miles easily when i was done. it will be hard to keep using that heart rate if all of my runs are that slow. but i have a feeling that my runs will get faster. i am only in the technique phase of this program, trying to teach myself how to run with this form, before i start the conditioning phase, so it is ok for now. breathing out of my nose wasn't that bad, i just had to keep thinking about it. my overall time was 44.55. i will humbly take that for now.