Now we want each of you to demonstrate the same diligence for the final realization of your hope, so that you won’t become lazy but will be imitators of those who inherit the promises through faith and perseverance.
-Hebrews 6:11-12 (HCSB)

Do you have perseverance?  It takes perseverance to inherit the promises.  Perseverance is long-suffering.  It is patience, as in a long temper.  It is a "keeping on, keeping on".  Perseverance also means, "delayed hope" (Prov. 13:12).  

A quick diagramming of Heb. 6:11-12 is this.  I imagine this is not perfect, but this is my attempt, to try to understand it better:

Now we want 
-each of you 
   -to demonstrate
       -the same diligence
       -for the final realization
       -of your hope,
       -so that you won’t become lazy
   -but will be imitators
      -of those who inherit the promises
         -through faith and perseverance.

My focus is on this word, perseverance.  It falls within the "imitators" section.  We want to be "perseverer's", who inherit the promises, through faith.  The writer tells us that, indeed, faith is not passive.  Real faith is proven through long-suffering.  That is how it works.

The author says, to do that, by imitating or following the example of others who are doing this.  Verse 12 is somewhat of a restating of verse 11, in which it says that we demonstrate diligence.  Diligence means earnestness or an enthusiastic going after.

Becoming Christlike, is a process to be pursued.  It takes diligence and perseverance.  These verses are in contrast to the verses that precede them, that talk about people who do not diligently go after Christ being formed in them (Gal. 4:19).

I like the Holman Standard Christian Bible (1), here, because they use this word, perseverance.  The King James has, "patience", which is the most common way this word is translated.  I found "longsuffering" in the ACV.  The NLT has "endurance", and The Message says, "stay the course", which I also love.  The other ones that use "perseverance", are The New English Translation and The Jerusalem Holy Bible.

There are "promises" that Christians want to see in their lives.  I was going to say "strive after", but I don't want to say that we make it happen.  However, we do have the paradox, that we need to be still and "be", while letting God "do" and "be".  But, there is also much that we "do".  We do "press on", to finish our race, which is a marathon (Phil. 3:14).

As a young man, I wrestled with the idea of, "waiting on God".  I found out that what this means is waiting like a waiter, at a restaurant.  In other words, it is not passive, and it is relational.  You are active, like the wise virgins, who kept their lamps going, while waiting for the call of the bridegroom (Matt. 25:1-3).

We have to learn to trust God, with all our hearts (Prov. 3:5) and not depend on our own understanding.  That is inheriting the promises through faith and perseverance.  In all our ways, we acknowledge him and he will make our paths straight, or direct our paths (Prov. 3:6).  It is a faith and patience thing.  We keep on, not losing our temper.

We don't want to become lazy.  The world is always dragging us down and back.  We have to work.  Faith saves you, but faith does not work in your life, unless you work it.  It is like having things, but you have to get up and do something, to put them to use.

We inherit the promises (2 Cor. 1:20) of God through perseverance.  Everyone who inherits God's promises has a hard life.  There are bumps, detours, losses, set backs, and betrayals; just to name a few of the challenges.  Things do not always go as planned.

But God has provision there, in the challenges to our faith.  We have to receive and take hold of it, and put it to use.  God provides for us when any bad things happen to us, and God compensates us for the deficits that the injustices of life place on us.  God is huge on justice (Psalm 89:14 & 97:2, Luke 18:7).

Perseverance is the way on.  Those that  persevere will inherit.  That is what it says.  It is a narrow path (Matt. 7:13-14).  If you want to live in Romans 8:28, seeing God causing all things to work together for good, you have to keep loving God, confirming your calling, for his purpose.  We persevere (keep faith-ing, working out a life of believing no matter what, like Job (Job 13:15)), and God works stuff out through provision and compensation.
I found the photo above on J. Michael Cunningham's blog post, here.
1. A review of the HSCB.