Hardware wallets! I just got my Ledger Nano S and I love it! (https://www.ledgerwallet.com/r/fed9?path=/products/1-ledger-nano)

Simple to use and I have peace of mind knowing my keys and bitcoins are secure from any hacking. If a Ledger Nano S costs you 5% of your total Bitcoin holdings it's probably worth it especially considering if Bitcoins continue to appreciate in value...