Satisfaction equation

While running, I came up with a formula to calculate how satisfied I will be with my training session once I am done. There are a few variables in there. Difficulty is the technical difficulty of the workout. The more difficult the workout, the higher this value will be. Am I trying to break new grounds for speed or distance for example? Environment is related to the weather conditions, is it hot, cold, windy, raining, etc? The more challenging environmental conditions are, the higher this number will be. Success is how successful I am in meeting the goals of the workout. A complete success would be a 1 where a partial success would be a 0.8 and a failure a 0.5 and cutting the run short 0.2. Motivation is whether I feel like doing the workout or if I am forcing myself to do it because I am having one of those days. If I want to do the workout, this number will be 1. If I procrastinate around a bit before getting out, this would be 0.8. If I have to bribe myself with all kinds of rewards this would be 0.5. The equation goes a bit like this:

Difficulty * Environment * Success / Motivation = Satisfaction

So a workout last week where I was trying to break new ground speedwise (1.5) in hot weather (2) and failed at my interval (0.8) still yielded a high satisfaction rating (4.8) since my motivation had been really low (0.5) and I had to really work at getting out of the door.

How do you keep satisfied when not everything is going your way?