You cannot win an argument with the weather
There is a conversation you have with yourself at the window, and it is always roughly the same one. It has been raining since four. The light went early. You said you would run this evening, and here is the evening, looking like that.
So the negotiation starts. Tomorrow might be drier. You could do something longer at the weekend to make up for it. Going out in this might even be the unwise choice, which is a comfortable thought and does not survive much inspection. None of that makes you lazy. It is what anyone does when a plan meets conditions they never agreed to.
What is worth knowing is that you will lose that argument most evenings, and losing it says very little about your character. You are holding the debate in the worst possible place.
The window is the wrong place to decide
Stand somewhere warm and look at cold rain, and every cost of going out is in front of you in detail, from the wet socks to the pile of soaked clothing waiting at the other end. The reason for going is nowhere in the room. It sits weeks away, abstract, impossible to feel from where you are standing.
Set the choice up that way and it is not close. The forty unpleasant minutes are vivid and immediate. The payoff is invisible. Then people take the result of that lopsided comparison and read it as a report on their discipline, which is a lot to conclude from a decision that was rigged before they made it.
Decide it earlier, and decide it smaller
The useful move is to settle it at a time when nothing is pressing on it. Sunday morning with a coffee, say, when Wednesday evening is a square on a calendar rather than a wall of rain. Name the days you intend to run and let that stand. When Wednesday turns up looking foul, there is nothing left to decide. You are carrying out an instruction that somebody calmer wrote for you.
Make a second decision at the same time, about what counts on a bad night. Twenty minutes might count. So might a loop to the end of the road and back, or whatever you would still be willing to do once the weather has taken all the appeal out of it. A short run in poor conditions keeps the habit intact, and the habit is the thing that has to survive the dark months. The full session you talked yourself out of does nothing for you at all.
Most of the cost sits in the hallway
Ask people what they dread about running in the cold and they rarely describe the running. They describe getting ready: the drawer with the gloves that were definitely in it, and the last minute of warmth in the hall before the door opens.
That part is fixable, and it gets less attention than it deserves. Put everything you need in one place the night before, so that leaving the house is a matter of putting things on and opening a door. It sounds like trivial admin. It also removes the ten minutes in which most people change their minds.
The weather stops being the subject fairly quickly
The honest version is that the first few minutes are genuinely miserable. You are cold, the rain finds your neck, and you wonder what possessed you. Then your body catches up with what it is doing, and by about the tenth minute the weather has turned into scenery. You are wet, and being wet has stopped being interesting.
The part that surprises people is how good the ordinary things become afterwards. A hot shower after a cold run is a different experience from a hot shower on any other day. So is coming back through your own front door. Small rewards, but they turn up every time, which is more than the usual promises manage.
Some nights the answer really is no
None of this means the weather never wins. Ice underfoot, a storm, an unlit lane with nowhere safe to run: staying in on a night like that is a reasonable adult decision and it costs you nothing. Work out in advance what would genuinely stop you, and you will be able to tell the difference on the night between a real obstacle and a strong preference for the sofa. Most people cannot tell, so they either go out in things they should not, or they treat every damp evening as a legitimate cancellation.
The seasons will do what they do, and no amount of resolve makes November behave like June. What you can change is where the decision gets made and how large the ask is when conditions are poor. Sort that out while you are warm and thinking clearly, then let the version of you standing at the window simply do as it was told.
You still will not want to go. Wanting to go was never the part that got anybody out of the door.
Written to encourage, not to diagnose. If something hurts or feels wrong, please speak to a doctor.