Am I overthinking?

I don’t expect anyone to read this, so thanks if you do. I just started XL 150mg this morning (9am) and about 30 mins after taking it I felt exhausted and like my legs weighed 1000lbs each. Is this just in my head? It’s currently 12pm and I’m still feeling quite sluggish.

Trying to stay positive and hang in there for a few weeks to see if the medication will work for me. Just feeling discouraged but I know I shouldn’t as it’s literally day 1