I am thankful for the obstacles I have overcome

This one is only honest in retrospect, and only sometimes. Some obstacles taught you something. Others just cost you years, and you'd hand them back tomorrow if there were a desk for that.

The defensible version is narrower. You're thanking the person who kept going, not the thing that made going hard. There's a real difference between crediting the storm and crediting whoever walked through it.

Think of one you're now on the far side of — a job, an illness, a bad stretch you no longer think about daily. You'd have said you couldn't. You did anyway.

That's the part worth thanking.