Um... contributing to net well-being? I mean, that's a fairly easy question - and it has more to do with mental well-being than physical - but let's keep it simple: If a person intends to do something good and then does that good thing, you have a good intention and then a good outcome, okay, that's cool - but you can also have someone who intends to do something bad, but then does a good thing. Some would argue that their is no distinction between the two - but I would argue that the distinction is the intention - if Hitler were to save a thousand puppies, for example, would that be different from like, some good dude saving those thousand puppies.
Yes, but only for the individual - because you can be a "bad" person overall and still do good things (same thing vica versa) - so for someone who intends bad doing good can have negative outcome (it could make them more sure that what they were intending to do is the right thing to do, while in reality it was very possibly just a coincidence) or it can be a good thing (it could encourage that person to do more good things, and doing more good things will eventually affect your intetnsions.)
SO, intention affects YOUR well-being, while that is small, it is indeed well-being as well.
And well-being is really easily defined, Tarik can larp all he wants, we have a definition we can use - and one I use specifically, the fact that medical professionals can't come up with a specific definition is fine, cause we're not using the definition medically, much more philosophically, and in general.
Well-being it just to generally benefit your mental and physical state.