Spoken like a true 20 year old who has no concept of what health at 75 looks like. The alcohol hangovers will last multiple days, you might have a lung condition that prevents you from smoking, your circulation will massively shit the bed off stimulants (think racing heart, cold sweats, feeling weak, anxiety) and opioids… well, opioids might be mostly okay except for the constipation I guess. Withdrawals might incapacitate you for months though.