How to inculcate gratitude

Q: How can I become a grateful servant of Allah Ta'ala? Even though I know that Allah Ta'ala has given me so many bounties, I still question why he has given others certain things and not me, and I often tend to wish bad for them. I know that this is wrong and I want to change, especially as it is creating a lot of unhappiness in my life. I know that I should look at those below me but I still seem to keep looking at others who have more things than me. I would like to become grateful to Allah Ta'ala for everything He has given me. How can I do this?

Early settlement discount

Q: Please advise if the following type of transactions are valid, not valid or improper:

A business has an agreement with a supplier to pay after 30 days from date of delivery with a limit of R50 000.00. 

1. The business puts a condition on all purchase orders, that should the supplier request an earlier payment, it will incur a early settlement discount of x% on a daily basis.

2. At times the business goes over the limit of R50 000.00 , hence early payment now becomes binding in order for the supplier to deliver further orders, can the business in this situation claim the x% early settlement discounts.