How to change our destiny?

There are two school of thoughts regarding this destiny. One is that destiny can not be changed and it is predetermined at the time of birth. Another school of thought is destiny can be changed by remedial pooja and by worshipping planets.
I am now coming to second school of thought as I will choose a optimistic way of life always.
A learned astrologer can examine and find out from a chart whether the destiny can be changed or not? The position of Lagna lord, Jupiter aspect and current dasa, bukti determines whether the remedial pooja done will be beneficial to the native or not?
Lot of eminent personalities who are handicap have made lot of accomplishments in spite of their weakness. Hence by taking a positive clue from them we have to try to change our destiny by doing remedial pooja, wearing Gem stone, Talisman, doing Homam and worshipping Navagraha temples etc.
Above all it is the God who is going to reward our efforts. As Saint Tiruvalluvar said in Tirukkural some 2000 years ago , even if a thing is not favoured by God ones efforts will see that it is accomplished!