Today our meditation may be like a wild stream rather than a smooth-flowing river. But by practicing regularly, and trying to bring that practice of mindfulness into our daily life, we can gradually find a flow of inner calm. We learn to appreciate the present moment and our relationship to everything we do is transformed.
As Matthieu Ricard says:

Daily meditation practice is a offering ourselves a moment of refreshment that we are happy to come back to. However there are days when it’s hard.
It can be frustrating for meditators, and not only for beginners, to keep on encountering the same difficulties, the same troublesome emotions. One can have the feeling that the practice is not working or that we are exceptionally incompetent, and so it is important to appreciate that ups and downs are normal, in meditation as in life.
Everything changes all the time, the weather, the seasons, ourselves. We are born, grow up and grow old. We have happy moments and sad moments. Somehow it is hard for us to accept this most basic fact of life. We would like to keep or repeat the fleeting magic of happy moments, when change is inevitable.
Each moment is new. There can be new magic but it will never be the same. By simply examining how we felt this morning, this afternoon, this evening, we can see that everything changes all the time. We might judge our practice of meditation from day to day, thinking, “Today I had a bad meditation, yesterday was a good one!” or “Once I had such a beautiful experience in my meditation. What does it mean? How can I have it again?” In fact the experiences we have in meditation are like the weather, changing all the time, sometimes clear, sometimes cloudy.
If our meditation seems mainly cloudy it doesn’t matter. Since we have been used to following our thoughts and emotions for so long, reacting to whatever comes up without being aware how they arise from our own mind, it is normal that it’s hard for our mind to stay still and just be present with the breathing.
Our practice is a mind training. Just as in physical training some people are more supple and some are more stiff, we may have more or less difficulty. In either case we can progress by keeping going with the practice. Real transformation comes slowly. Rather than looking at the inevitable ups and downs we could consider if we have managed to change over a year or more. Often the changes are not what we might expect. We might not feel particularly serene but have a more profound appreciation of the world and other people. As our perceptions change it is as if the world we live in has changed.
From Charles Hastings’ course Exercises for a kind heart:

Matthieu Ricard insists that our mindfulness should be “caring mindfulness”, leading to a truly altruistic mindset. This is an essential element of Imagine Clarity. Charles Hastings’ basic Meditation Practice Foundations are followed by a precise training in kindness and compassion: Awakening the Heart.