Often, I have found that having discipline is what matters the most to reaching a goal. Have a process, follow and repeat it every single day. Most success comes from repeating the same thing every day and doing it, rain or shine. From a personal standpoint, I had only minor victories. However, I reached these personal goals by having a straightforward process and following it every day. I have lost half of my weight (from 300 pounds to 150 pounds) by eating boring meals made of protein-rich food and being active at least one hour a week for two years. I completed my Ph.D. in 2.5 years because I worked 8 hours every day, including weekends. The ultra-marathons I ran are the results of running at least 70 miles a week for two years.
We are often tempted to go off-track. Skip a day. Or two. When we give up, we tell ourselves a lie: skipping a day or two will not significantly impact the outcome. In reality, we are not holding ourselves accountable and not respecting the contract we made with ourselves.
Your process/guidelines can (and will) change over time. The willingness to follow your process should not change. And the dedication to do what you committed to doing should remain the same.
Discipline is not only what will help you progress every single day. It will also guide you when you are lost. If you do not know if what you are doing is worth anything or if you are making the right decisions, all you have to do is to have discipline and follow your process. There is always light at the end of the tunnel.