if not, why not?

High Tempo asks...

The Old testament laws were set specifically for old Israel, correct?

Yes, the 613 Mitzvot of the Mosaic Law were given specifically to the descendants of Jacob.

This was done because Israel was God's chosen nation, correct?

The descendants of Jacob (Jews) are called God's chosen people because they were given the Law and the promise. Not the other way around, as you suggest.

Do you not aspire to be as good as the people of God's chosen nation?

It's not really about what I aspire to. What it's about is what God intends for me, what God wants me to become.

If not, why not?

Because I know that fall short of God's standard. I recognize that I am unable, under my own effort, to reach the goal which God intends for me.

I know that it is only through God's power, through God's effort, that I will be measured acceptable by Him.

If so, why do you not follow Old Testament laws?

Because the Old Testament law is utterly unable to make me the person God intends me to be. The Law fails to achieve the goal that God sets for me.

Fortunately, God has fulfilled the Old Testament law, he has filled out the Law to its full meaning in the person of Jesus.

I follow Jesus, who is the reality. The Law was and is a shadow of the truth.

More practically, no instruction is given for followers of Jesus to first become Jews, and follow the Old Testament laws. (According to the letters that Paul wrote, there were Jews that believed Gentiles should first become Jews, before they came to Jesus, but Paul makes clear that idea is wrong.)