Karma again!!!

[Nanda Kumar]

Jonathan, instead of asking questions, let me first briefly try to explain
what I understand of Karma so it'll be easier for you to explain to me.

There's the dual aspect of karma ((in)action) with respect to Sanatana
Dharma. 1. The Bhagavat Gita expounds that, one should act without
expecting the fruits of one's work. 2. The karma with respect to fate
(which I suppose is what you're really interested in, going by your
previous mails on the subject). Again the scriptures expound that one's
action in the past will decide his future (every action has an equal and
opposite reaction). Krishna in BG says if one realizes himself his
prarabhdha karma will be dissolved. But the Upanishads expound that
even if one realizes himself he will have to live in his body till he
dissolves his prarabhdha karma by right action.

What I infer from this is that Karma (right action) helps in purifying the
mind and soul, makes one ripe for jnana and hence quite practical.

So where exactly is the concept of convinience with respect to karma?
And again how does it override the concept of Tat tvam asi?