Newton's 1st law states that an object at rest tends to stay at rest, while an object in motion tends to stay in motion. Interestingly, there are a number of physical examples that teach us that gaining that initial momentum to transition from rest to motion is more difficult than maintaining momentum. For example, the water strider, pictured below, is able to stand and skid across the surface of water due to a phenomenon known as "surface tension."
There are weak molecular attractions on the surface of the water which can only be broken by a certain amount of pressure per unit area - in the case of water, about 0.000416875 PSI. (Note: standing on the water without breaking the surface tension is not the same as "floating" - a boat floats because of the principle of buoyancy, which works by part of the boat being submerged underwater until it displaces enough water to equal the weight of the boat.) In fact, if the little bug there in the picture were to step too hard on one of its legs and break the surface tension, it would start to sink. It requires more force to make that initial break in the water than it does to continue sinking down into the water once the surface tension is broken.
Static friction is another example of this same principle. Anyone who's ever rearranged their furniture is familiar with friction (it's what makes the dresser hard to slide across the carpet), but did you know that friction is stronger when an object is not moving than when it's moving? That means that it's more difficult to get the dresser sliding than it is to keep it sliding (pro tip: once you've got it moving, try not to stop).
What about economics? You may be familiar with the phrase "it takes money to make money." Adam Smith expressed it this way in The Wealth of Nations: "When you have got a little, it is often easy to get more. The great difficulty is to get that little." What about your social life? It's harder for a young man to work up the courage to talk to an attractive girl than it is to continue talking to her once he's started.
There are dozens of examples of this phenomenon - it indeed seems to permeate human existence. I didn't state the entirety of Newton's 1st Law: an object at rest tends to stay at rest and an object in motion tends to stay in motion unless it is acted upon by some force.
It's been quite a while since I've written a blog article. It's not for lack of ideas, and I have numerous outlets for doing so, including this one, which is, incidentally, the one on which I've abstained from the longest. For a while, I was an object in motion, steadily taking note of ideas I had, researching them, and then bringing them to fruition in the form of a blog post. Somewhere along the line, some force began to slow that momentum until I finally stopped. With this post, I'm rekindling a fire. That's another example of overcoming initial opposition, by the way - once a certain threshold of heat is reached in the presence of kindling, the first spark is lit. To keep a fire going is as easy as providing more wood, but to start a fire (without modern implements such as matches) can be very difficult.
In my experience, keeping God's laws, doing good works, and preaching the gospel - in summary, living God's way - are all subject to this same phenomenon that I've laboriously drawn your attention to. It's more difficult to get started doing the right thing than it is to keep doing the right thing, and it's likewise easier to continue doing nothing rather than to start doing something good. About 2 years ago, I wrote an article that compares the Holy Spirit to a fire based on 1 Thessalonians 5:19, which says, "Do not put out the Spirit's fire." The Holy Spirit is a spark provided by God which becomes a fire within us, and we then choose whether to keep the fire burning or not.