Ajahn Sucitto describes the connection between joy and samadhi in an article in which he makes clear that “through this process of bringing happiness into body and mind, the mind is naturally concentrated. That is samādhi.” So, concentration is fostered by joy, not the forceful exertion that many expect it to be. You can find his article here: Samdhi is Pure Enjoyment
Gil Fronsdal has an article that introduces concentration and shows its relation to mindfulness. He describes several ways of exploring the breath in meditation that can help our minds to become more unified and focused. You can find that article here: Concentration
For those times when attempts to settle the mind are not working and doing more harm than good, you can find a very different approach from Cara Lai in her article on how to “Undomesticate Your Mind.” She describes an approach that’s more akin to natural awareness than using an anchor. You can find her article here: Undomesticate Your Mind