"Welcome to your life". The life that begins when satan captures you.
"There's no turning back". The process is irreversible and you cannot go back to where you were before satan captured you.
"We will find you acting on your best behaviour". I think this is because when people know satan is about to get them, they start to do the right things they always thought they should do but kept procrastinating. The hope is that this good behaviour will grant salvation from satans power.
"Turn your back on mother nature". It is human nature to be bad ( not everyone is like this though ), so when you start doing good things you are going against your nature.
"Everybody wants to rule the world". Well I think only some people do, but certainly not everybody. Satan may see this in everybody though, but thats just his paranoia.
"There is a room where the light wont find you". When satan captures you, Jesus or even God cannot save you. No amount of prayer will work.
"Its my own design". Similar to "we are all just prisoners here, of our own device" in hotel california. Suggesting no one tricked them into the trap. For the power trap, this may be true, no one leads you to want to rule the world, but they may suggest it to you - that you are worthy of it, or they may just encourage you when they see the trait in you.
"Its my own remorse". Well now you've seen the consequences, there is remorse.