You can lock your account by a secret question.
PSA: ACCOUNTS WILL BE LOCKED IF THE SECRET QUESTION IS USED TO RECOVER ITYou can change your email address to something like this guide, noone can hack that account.
Make sure that your email address is secure. If you don't want to set an email address, use something like yourUserName@invalid.bitcointalk.org; don't use a random nonsense email like y@x.com, since somebody might create that domain/email.