Hi Alvin:
Yes, we definitely build up according to our inclination (bhakti) and capacity. The latter, "capacity," becomes a much bigger factor once our energy is flowing abundantly. Then we are limited by the energy flow and corresponding rate of purification we can tolerate in daily life, rather than by how much more we can pile on in practices.
Katrine spoke about this shift quite beautifully in one of her early posts. If I can find it, I will add a link here. My own way of explaining it is to say that for years I was chasing the goddess, and then one day I realized she was chasing me! That is what happens when kundalini gets active. We move from being instigator to being partner. Being a partner with kundalini (our active inner energy) is tweaking and letting go, rather than hammering. In that condition, if we are hammering, we will get hammered. That is why the folks around here with active inner energy raise an eyebrow when you talk about doing umpteen rounds of bastrika, kumbhaka, etc. I mean, that is way more than is necessary once the lights go on inside, and probably long before that, as Shanti points out in the previous post.
It is really easy to get the message and ease up on intense practices when the energy takes off (and/or crashes). We learn to let go -- the greatest lesson we can have in life, coming directly from within us. Then we don't need books and all sorts of advice anymore. We become the book and the advice is in our increasingly radiant nervous system. Pretty good deal, actually.
In that sense, yoga is not like physical exercise, though there are still parallels -- conditioning ourselves for a particular function being the most obvious. But once the spiritual conditioning reaches a certain point, a vast energy and intelligence is awakened within us that will carry us forward along with our practices in moderation. That is where yoga departs from the analogy of physical athletics and enters an entirely new realm.
We are obliged to conduct ourselves accordingly. To ignore the reality of where we are arriving and how things work there, hanging on to other models we have been using (like athletic conditioning), can lead to some tough lessons in the school of hard knocks. The lessons don't have to be hard to learn, especially with a few folks around who have already or are currently going through the same thing.
Of course, all of this rides on inner silence, cultivated in daily deep meditation. Have I brought that up lately?
The guru is in you.