Why we can't experience joy

I get up in the morning.  Feed the dog.  Feed the bird.  Go to work.  I force myself to do things: have dinner with friends.  See a movie.  I am not happy. I'm walking through life like I'm in a trance.
Reading the post on DS, I see other people going through various stages of what I'm experiencing.  Some are months out, some are years out.  None of us are experiencing joy.  Why is that? I wondered.    Is joy so elusive that once your spouse is gone you're doomed to go the rest of your life in sadness?  Is there no end to this?
I refuse to accept this.   I refuse to accept that every second of my life will be spent feeling this  way.  I've know alot of us feel this way because we keep asking older members how it will feel when we reach their month.  We're always hopeful that they will tell us that we'll feel better.  But then we hear from people who are years out and they're still suffering.  They're not experiencing joy and the question for me became why?  Maybe I'm wrong, but I think the reason we're not experiencing joy is because we don't know it.  In other words, at some point in this journey, joy comes back and we ignore it.  Because joy for us is defined as having our spouse back.  So insert the name of your spouse when you think of the word joy. 
Over the past months, I keep asking myself when will I be happy again.  When will my life reach this "new normal" people are talking about?   Well, I think I know the answer.  Unless I change my definition of joy, I will never be happy again.  I'll be doomed to just walk through life.  And at the end of it, I'll have regrets.  Big ones.  So the only way I can experience joy is to take charge of my life.  I've got to stop just walking through the days and weeks to come and actually do something to change my definition of joy. 
I've come to the conclusion that one of my problems is that I expect the "new normal" to define itself.  I expect it to just happen.  Actually, it's the reverse.  I've got to define it.  I've got to decide who this new person is.  And I've got to define what joy is.  It's no longer my husband. And it's not going to define itself on it's own.  As long as I define joy as my husband, then I doomed to sadness.  
So it's a task for me because it requires me to be an active participant in life, not the passive one I have been since this horrible thing happens.