My LSD is about 58% max

I woke up with a HR of 49. After a couple of hours of doing things around the house, including going up and down stairs, I measured my HR just before I started my stretches that include 33 sit ups and 10 push ups. It was 50. After my stretches it was 52. After my 3 1/4 mile run at my long slow distance (LSD) pace of about 10 minutes/mile, my HR was 88. Using the traditional formula for max HR, my max is 220 - 68 = 152. My HR at the beginning of my run was 34% max, and my HR at the end was 58% max. That's about right for my LSD goal at this stage in my training. Later on after I have my weekly distance up to 33 miles, I'll start doing speed training, and during those bursts, I'd like to get my HR up to about 85% max or 129 or so. These numbers are interesting, but to me it's more important how I feel. During a LSD I should feel rested and should enjoy the run, and I do. I'm a firm believer in LSD while increasing distance!