Daily prayers/fasting are mainly forms of worship... I never felt fasting was *good for my soul*, on the contrary, it makes me grumpy all day but I fast because it is my duty to worship God...
By the way, Abu, do you feel God owes you anything? anything at all? A lot of Muslims, surprisingly, do think that God owes them *rewards* if they prayed to him/fasted, etc. Or that He must *justify* particular rituals. I hope you're not one of those, because in this case you didn't understand the true message of submission to God, which is summarrized in this one verse:
6:162
Say. Surely my prayer and my nusuk (rituals) and my life and my death are (all) for God, the Lord of the worlds;
[your entire life is God's].
And by the way, a big part of the Quran is encompassed in these two verses:
31:33
O mankind! do your duty to your Lord, and fear (the coming of) a Day when no father can avail aught for his son, nor a son avail aught for his father. Verily, the promise of God is true: let not then this present life deceive you, nor let the deceiver beguile you, in regard to God.
31:34
Surely God is He with Whom is the knowledge of the hour, and He sends down the rain and He knows what is in the wombs; and no one knows what he shall earn on the morrow; and no one knows in what land he shall die; surely God is Knowing, Aware.
[Life, no matter how long, will eventually come to an end, so let's not be deceived by it].
I beleive that prayers/fasting are forms of worship as well - i just don't think they are necessarily worship to God in the classic theological sense that a lot of people think them to be (i.e. that God simply wants to be worshiped). i think that there is a much deeper reason behind these acts of worship - they are for the benefit of us rather than the benefit of God (of course i don't mean rewards in heaven etc., but like i said i think they benefit our souls).
I've never felt that God owes me any rewards or that He must justify anything - I do relaise that it's a bit silly to ask an all-knowing all-wise God to justify anything. I do realise that Islam is all about submission to God - this means i do good that my God-given soul and intellect tells me is good, and i forbid bad that my God-given soul and intellect tells me is bad.