you can create a conscious adrenaline trigger and just to prove the point let's try this experiment -
close your eyes and imagine a dangerous situation you have been in, a good example will be a fight as a kid. visualize the situation with maximum detail. You will notice your heartbeat has gone up and you start to experience muscle tension around your arms and it's very likely you will clinch your teeth, your mind has triggered the adrenal gland to prepare you for a fight. multiple studies have shown that visualization triggers the same areas in the brain as a live experience - and the body reaction is set off. to train this you need to create an anchor with the desired response.
to practice this you just need to anchor the feeling