OP, you've only posted twice on this thread so we don't have a complete picture, but you sound a bit depressed. I understand. I have been there. It occurs to me that you should have your T level tested. Low T can cause depression and is common in older distance runners. It doesn't even have to be clinically low. It can just be low based on your own normal level.
If you're in the 200s (on the lower side of normal), you should take steps to boost T levels. T supplementation is banned, plus testosterone supplementation hinders your body's ability to make T on its own. I'm not a fan of T supplementation for this reason, but you could try it for a month to see if low T is part of the problem. If it is, you could stop taking T and work on ways to boost T naturally. Or, you could just skip the T supplementation and go straight to ways to boost T naturally. That's what I would recommend. (But you should still get a T level blood test to see what your base T level is before you start. Then, you can test again in 3-6 months.) These include...
Weightlifting at least 3x/week.
Sprint 8 workouts ( look it up). It's similar to HIIT. You go hard at something for about 30 seconds and then rest 90 seconds and go again. You can do this on an elliptical, spin bike, steep hills, or you can do sets of weightlifting reps going to exhaustion in 20-30 seconds, then waiting 90 seconds and repeat. I do this at least twice a week. At the gym, I'll do 3-4 sets of an exercise with the last two sets going to total exhaustion. Then, I'll do a couple more sets with another lift. I try to get 8-12 lift sets to total exhaustion at every gym visit. I would suggest that you NOT do sprint 8s by running (except for hill repeats). All out sprinting will probably result in injuries for aging distance runners.
You should be getting around 120g of protein every day split into about 30g doses.
Sleep. If you're not sleeping well, it will adversely affect T level. I'm not going into this because it is a LOT more involved to explain it.
Change your workouts and track your progress in your new workout. You might do sprint 8s up a hill and track how much farther you can get each week. You might do a Billat 30/30 workout (look it up) and track how far you can get in 16 reps.
For recovery days, I do an easy trail run where I try to keep my average HR as low as possible while still finishing in about the same time. It's fun to take a workout that is otherwise boring and turn it into a challenge.
I'm older than you, but I try to keep my T level over 500. It was 735 recently. Twenty years ago when I was just a distance runner, it was 215.
Anyway, I hopes this helps.