Obstacles are to be expected: There are a number of predictable obstacles that arise on the inner journey, along with several consequences that grow out of them. While these can be a challenge, there is a certain comfort in knowing that they are a natural, predictable part of the process.
These predictable obstacles are 1) illness, 2) dullness, 3) doubt, 4) negligence, 5) laziness, 6) cravings, 7) misperceptions, 8) failure and 9) instability.
From these obstacles, there are four other consequences that also arise, and these are: 1) mental or physical pain, 2) sadness or dejection, 3) restlessness, shakiness, or anxiety, and 4) irregularities in the exhalation and inhalation of breath.
These four arise because of the other nine. In one sense, it seems that all thirteen of these could be grouped together in one sutra. However, it’s useful in practice to see that these four come as a result of the other nine. If you look at these four closely, you’ll see that these are relatively easy to notice in yourself, compared to the other nine. When you see one of these four, it is a clue to you that something is going on at a subtler level. Then it is easier to see, and to adjust.
These four are good indicators of the subtler obstacles: If you think of these in terms of other people, notice how easy it is to observe when someone is experiencing pain, dejection, restlessness of body, or irregularities of breath. You may not know the underlying reason, but you can sure spot the symptom on the surface. Similarly, we may not know that something is going on inside with ourselves, at the subtler level. Yet, if we observe our own gestures, body language, general level of pain and mood, we can more easily see that something is going on at the subtler level.
Seeing can lead to making changes: Once those surface four lead you to awareness of the subtler obstacles, then it is much easier to take corrective action, to get back on track. At first, this can sound like a lot of intellectual analysis, but it is actually quite simple and extremely useful. You may discover that a simple refocusing back to your practices, your personally chosen philosophy of life, or useful attitudes will weaken those obstacles. Most importantly, it can be a reminder that you have temporarily lost your focus, and to return to one-pointedness.
Excerpts from Article on Yoga Sutras 1.30-1.32 at swamij.com