Before the metta is continuous, the five hindrances may arise to hinder the progress.

1. SENSUAL DESIRE (kama raga)
Sensual desire arises commonly with an attractive object. This is one reason why we do not choose the extremely intimate person as the first object and also, based on the same reason, why we avoid one of the opposite sex. Even when giving metta to the good friend, you should avoid thinking of sensual moments (e.g. sightseeing etc.). Calmness and joy that arise abundantly in this meditation should also not be attached to when they arise during practice. One may note the "desire" or "attachment" with mindfulness till it goes away. Always remember not to be attached! Mindfulness is the key to this. Alternatively one may radiate metta to all beings for a short while to offset the attachment. Then bring one's mind back to the pure and unselfish state of metta.

2. ILL-WILL
Ill-will arises with the repulsive object. That is when we are sending metta to an unpleasant or hostile person. If anger arises one may resume with the persons (lovable) one started with. Ill-will may also arise with frustration or unpleasant sensations. In such a case, try to ignore it and persist with the metta. If it fails, change to a more comfortable posture or setting.

3. SLOTH AND TORPOR
This sluggish state of mind that can come with peacefulness often makes the meditator fall into deep sleep. Therefore when the mindfulness weakens, one has to be more energetic in arousing the metta. For example, one may radiate from one aspiration to another fairly rapidly. One can also try to make the metta more intensely emotional. Doing more metta in the walking posture also encourages a more energetic flow of metta. One has to be very energetic to be able to do these. Activities like washing the face, rubbing the hands, sitting in brightness and open space, suitable conversation or reflection of the dangers of laziness and benefits of energy are general steps that can be taken.

4. RESTLESSNESS AND WORRY
Restlessness and worry arise owing to lack of mindfulness. If we have sufficient basic mindfulness, we would be able to watch that restless state or extraneous thoughts when they arise. So even if the mind does wander, we will soon be aware of it. Therefore we should make it a point to note the thinking as soon as it has arisen, then return to metta.

In the preliminary arousing of metta, when thinking is predominant, we have to be careful that it does not become uncontrolled, e.g. we may think of the person, then we think of what we did together. This may go on for some time before we realise we have forgotten about metta bhavana. Therefore to facilitate deep concentration one should stay with one person for an extended period of time. And when arousing metta, care has to be taken not to "overthink". Once metta has arisen one has to maintain its flow in a way that it may deepen.

5. SCEPTICAL DOUBTS
Sceptical doubt regarding the Three Gems or the method in the practice of metta may arise due to the lack of understanding of the Buddhist teachings etc. Here one has to note a sceptical "doubt" etc. till it is put aside. Another way is to reflect again on the benefits of metta and the danger of anger. If one tries hard enough one will progress and doubts too can be cast aside. Having an experienced guide at hand to clear one's doubts concerning the practice is important.