Positive feelings

 I think each individual is able to make his/her own scale.  Pick a time that you feel pretty much neutral and call that 0, then from there you can take maybe an incredible time and call it +5, and take a time that you're feeling really down and call it -5.  Then, you'll have a scale that you can measure feelings.  This is just an idea though.  There are many ways to do this.

I especially don't feel the need to measure experiences or emotions.  My joy or non-joy comes from the feeling itself.  I believe they are all unique.  A lot depends on where I am within myself when the feelings come and I am usually at a different place so each experience is good and new in and of itself. 

You can't really, different people measure different emotions in different ways, even simple sensation like pain is defined the same amount of pain in different ways. Also, since we change all the time we might define things differently in different times of our lives. 

Why would you need to? 

Feeling feelings is relative.  Time is the best way to measure... The first thing I think about when I wake up and the last thing I think about before I fall asleep... Ah, but throughout the day that's the key... Man, I can't get you out of my ahead!!