Joy........

ok, so my mentor and I were talking about joy last Friday. and it was very interesting how the conversation developed, and our perception of what joy is may have changed. since Friday, many people have used the word joy, and I have carefully noted the way people mean joy, or what they mean by the word joy.
most people use joy in place of happiness. perhaps it is because, they were more happy than they would be normally so they needed that extra word other then happy to describe the feeling.
my mentor and I were talking about where we think joy comes from. is joy an emotion, like happiness or anger, or is it something else? is it something that is given to us?
I asked my sister what she thought joy was, and she said ‘it’s happiness. it’s contentment.’ joy is what you feel when you are content. when you are happy with what you have. but then if joy is only when you are content, then you cannot be joyful all the time.
in 1 Thessalonians 5 it says ‘Be joyful always; pray continually; give thanks in all circumstances, for this is God's will for you in Christ Jesus.
the part Im focusing on is ‘be joyful always.’ how can we be joyful always?
I have always thought joy was an emotion that we felt. but I don’t think we can have one constant emotion whilst others emotions change. and so what IS joy, and where does it come from?
is joy something we have? or something we are given?
in nehamiah it says ‘the joy of the lord is our strength.’ which say to me that the joy belongs to the lord and it is that which is our strength. and so is it given to us? do we need to accept the joy from the lord to be able to be joyful always?
as I asked even more people, one person said that they think joy is a discipline. that makes sense to me. there are many disciplines that we need to do as Christians and so joy could be one of them. it makes sense because it takes a lot of work to be able to be joyful always and we have to trust in and rely on God for his help and provision.

This is just the beginning of my interest into what joy is, so please if you have something to add, please comment, i want to know what you think :)