And there are services now which automate this. For a management fee (generally 0.025%/year) you can set up automated recurring deposits, choose a risk tolerance, and let the algorithm continuously rebalance your portfolio automatically in a tax-efficient way. Just click some nice big friendly buttons and enter your information and forget about it, and watch your portfolio grow (or drop, with the market).

I work at a startup (https://www.sigfig.com) that does this, and lets you view in-depth information about how your portfolio is performing through rich charts and tables on our site and mobile apps. Our competitors (https://www.wealthfront.com/ and https://www.betterment.com/ among others) offer a similar service with slightly different value props.

There's really no excuse anymore for not signing up for something like this. It's insanely easy and ridiculously cheap. Like, maybe an hour to set up with zero paperwork to send in, and a tenth of the cost of an active fund.