We have to keep our noting up as consistently as possible. Sometimes when things seem to be going well for us, that can be a cause to let our guard down, but to do so would not be conducive to our long-term happiness. If we are not attentive to the good things we experience in life, then when we face difficulty we will think that difficulty is the predominant condition when that is probably not the case.
The central truth of all arisen phenomena is that they are impermanent: anything that has a beginning also has an end. If we allow ourselves to become complacent in our noting during the good times, this tendency promotes the view that happiness comes from external sources. In reality, external influences can only give us a temporary relief. That is why we remain satisfied with our success only briefly before we become interested in a new and better experience.
We need to train ourselves to reach from within for satisfaction rather than seeking answers from external stimulus. This means that we need to learn how to become mindful more often than we are not. In the beginning this will seem like a challenge because the untrained mind is very active constantly looking for something new, exciting and interesting.
However, over time and with practice, we can learn how to take satisfaction from the peacefulness that comes from noting what is happening right now. The mind that is satisfied in the present is much more conducive to long-term happiness.