Whatever is comfortable should be fine. Puja is about Love, all else is secondary to that. Whatever distracts you in your worship, you will want to eliminate.
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jai jai ,
very nice advice :yes:
of corse , yes we should sit lower if we can but only if we can , and of course we should bow down infront of the deitys upon entering the room , but some with bad backs canot easily do this either , in this case one can touch the ground with the right hand then touch that hand to the forhead as a mark of respect ,
the most important thing is the state of mind , if we canot physicaly show humility then mentaly is just as good .
one important thing in a puja room or temple it is not respectfull to sit with ones feet pointing towards the deitys so to sit on a stool one simply tucks ones feet under or as you say crossed at the ankles .
nor should we sit with our backs to the deitys , all just simply marks of respect
namaskars :namaste ratikala