I can add on the tiredness point with running, it sounds quite a bit to run 8 kms without having done so for a while, so it sounds like simply getting to a point of over exertion that you imposed onto your physical body. So you can have a look at seeing why you decided to run so much if you had not been doing so regularly to the point of exertion, what drove you to want to run that length without considering your body? I've had that at times where I would want to be so disciplined in going jogging every day that I was overlooking how there was some time needed for my body to recover from it, so instead of doing it daily, it's a one day and one day off thing. So what I learned was to not push myself beyond my limits because of wanting to satisfy an idea of myself as 'disciplined' and instead learn to hear my physical body, also taking it very easy with exercise if I know my body is going through processes and discomforts and pains and the rest of it, so, sounds more of a point to see what 'drove you' to want to run that much all of a sudden, how you can instead create a more continuous routine for your exercise that isn't as strenuous as what you've described and where you go also considering more your body in it, the potential result of 'going all for it' in one go as you've described above.
Tiredness is normal during the first weeks/months of starting to run, over time one builds a capacity to recuperate faster, but this comes also with consistency in doing so, therefore in my case I don't experience such exertion any longer, but I've also added days of 'no jogging' in between to allow my body to recuperate. Though as Anthony explains, sure there will be that 'push' that is needed as with any exercise really, and only over time it becomes easier as well and consistency in doing so.
In terms of making it 'self expression' - it is more of a decision of what you decide to express, seeing for example what is your motivation or drive behind it, being aware of your physical body, not getting to a point of satisfying a 'goal' in your mind of certain length to run, but to go listening your body as you do it, and sure why not then it becomes an expression of you with your body and developing a condition as your body that becomes more stable over time with exercising.
If you can share back what you've noticed in these points, go ahead.