I will take the advice in here to consideration planning my next few weeks. The workout today was definitely challenging, especially mentally. Partially because the gym thermostat was turned up higher than I like and the fan over the treadmills was broken. I certainly strongly considered stopping or cutting it short or switching to 400s instead of 800s or turning down the pace two clicksmany times during this workout, which is not uncommon for me during hard running in general.
On the other hand, I have not been getting sore or hurt anymore like I had been earlier on in my training. This could be to toughening up through general fitness from running. Also could be from the regular strength training, especially core training deadlifts, weighted crunches, hanging leg raises etc all of which have become regular parts of my routine. Could simply be from only running on the treadmill now and the surface being soft and easier on the body. I think my form is got much better as well and has been a priority. My stride has become smooth even running at 6:30 pace my footsteps are light and quiet on the treadmill. Normally totally silent running at easier paces. All that to say
I don't feel any soreness right now, as if I had not even run the workout, and don't expect to feel much DOMS tomorrow at all, if recent workouts are any indication.
All that being said, I would prefer not to keep pushing the envelope with my workouts week in and week out. It can be stressful to think about planning them in during the week and knowing how challenging they will be can make me dread starting them (though usually I feel incredible after it's over).
If I had run the same workout today at 10 sec/mile slower, It would have still felt hard, almost indistinguishably hard mentally and I would feel much less accomplished afterwards because I was already able to complete that workout over a month ago. I feel a bit stuck in the sense that I would like to improve each workout in some dimension if I'm capable of doing so.
The alternative to me would be something that isn't hard but harder than easy.
Lets suppose I should be capable of running a certain distance 7:00 pace based on my other times, but my best time to date in the distance so far is only 7:20pace, I am tempted to start my next tempo run for that distance at 7:10 pace and try to hold on.
If I'm not doing this, I am going to want to run it at like 7:50 pace and just relax and cruise. It's very hard for me to find a gear in between pushing my limits or purposefully holding back and enjoying it.
Not sure where I am going with all this but it helps to think it through by typing it out