a Needle in the Chest

I have a few cycles under my belt and i have spot injected almost everywhere, but today i decided to suck it up and pierce my chest, the inserting and aspirate was all good but as i injected the gear it hurt pretty bad, i had to inject a turtle speeds. Is there a reason for this? i used a 23gauge 1". Is it because i might have been flex alittle? Or maybe cause i worked my chest out 2 days ago? Any ideas.

that muscle is prob the hardest muscle with the least amount of fat on it.

when i did mine it felt kinda weird going in and after as well. a hot shower and some massaging did the trick