Remember the Vision
Starting anything can be difficult, but there's a unique challenge to long-term endeavors. Sometimes we don't see the fruit of our efforts for many months or years. Especially when the thing we set in motion is happening in the background. In other cases, sometimes we are too close to something to remember the vision in the first place. And in these cases, we're liable to forget why we started in the first place.
When you start something long-term, be it a life insurance policy or a relationship, it's important to set a vision---why are you taking this step? What do you want from this product/experience/effort in 10 years, or well beyond that? And perhaps more importantly, how will you maintain this vision?
You create purpose around something when you set a vision and commit to it by writing it on paper. Then, any time you lose sight of the important things, you have something to come back to, literally. This makes it easier to keep forging ahead, even when it's difficult, tedious, or even frustrating.
Many of the most worthwhile things in life are things you do for the long haul. Since none of us know how long we'll live, or know what it's like to live a long life until we do, some commitments have unforeseen obstacles and challenges. By being clear on your "why," you give yourself permission to keep going even when it's tough.