As long as you are in motion, and experiencing a relatively good workout that challenges your physical capacity, as a regular practitioner - you are in the clear.
You can set personal goals for your self while running: concerning measure' of the distances you go, how fast you conduct them, and when done so. I personally recommend that when you run/jog you go at a comfortable pace that is suiting for you. Whether fast or slow, and maintain it until tired or completed.
Bursts, or sprints are nice' when you feel you have the energy, to increase your performance. But I see that you are preparing for an endurance event, so just improve resilience and strength.
Always, in some way, try to improve your limits by doing something outside the bounds of normal. Go a little faster, a bit longer, a lot farther ... in moderation.
Oh, and music, don't forget inspiring music.
