3 life hacks that will save you up to 10 hours a week

There are 168 hours in a week.

We spend too many of them doing routine things like shopping for groceries, washing hair, and picking out clothes.

Here's how to get your time back.

Cut down on cooking and shopping for groceries.

If you live in New York or a similarly ridiculous city, heading to the grocery store takes forever as the checkout line slithers around Trader Joe's like a never-ending retail snake, which takes at least an hour total. Then you schlep home with all your goods, adding another 15, 30, or 45 minutes depending on where you live. Then, exhausted, you can actually start cooking.

According to the American Time Use Survey, men spend about 20 minutes a day on food prep and cleanup, while women spend about 45.

But startups are there to help. If you want to outsource the grocery-getting process, sign up for Blue Apron, a subscription service that will send you three meals a week at two-, four-, or six-person portions - at about $10 per person per meal. It's doing well: as of November, the service was sending out a million meals a month. This should save at least two hours a week.

Or you could stop eating entirely. The startup Soylent wants to "disrupt the food industry" by making it unnecessary to ever eat food again - just slurp up their nutrition-loaded smoothie. Needless to say, going on a Soylent-based diet would save five or more hours a week, so long as you're ok with the taste.

Washing your hair.

The average shower lasts about eight minutes. But if you're taking care of your locks, as many women and some men do, the then you're looking at a much longer routine. According to the Mail Online, it's another 15 minutes on blow-drying hair and another 15 minutes on styling - so a full 40 minutes a day on grooming.

But here's the thing: not washing your hair may actually be better for your look. Kim Kardashian recently blew up the Internet by telling Into the Gloss that she only washes her hair every five days, a habit that stylists agree with.

"Hair washing is very individual so there is no perfect amount, but if you have normal to dry hair, which Kim's hair appears to be, then every five days is a good idea," stylist Andrew Bidwell tells the Guardian.

"If your hair is finer than Kim's, then you will probably need to wash your hair more often, say every other day, but you should only wash the scalp level, so it's best to stick to the part underneath. If you wash your hair all over it will end up dehydrated."

So if you only wash your hair every few days, you'll be saving 2 to 4 hours a week.

Deciding what to wear.

Ikea recently did a study of morning routines of 8,292 people in eight major world cities, like New York, Mumbai, and Shanghai. The furniture company discovered that people averaged one to two hours of prep before they got out the door, and they discovered that one of the biggest pain points for people - especially women - was deciding what to wear the next day. So Ikea designed "a freestanding mirror that has a rack on the back for hanging clothes and jewelry," which Fortune reporter Beth Kowitt says helped stop "morning panic." It should save time, too - like 20 or 30 minutes a day depending on your morning habits, which should translate to 2 or 3 hours a week.

Some people go even more aggressive. Barack Obama wears the same suit every day and Mark Zuckerberg wears the same t-shirt every day for the same reason - their mental energy is better spent on making executive decisions, not what they're going to wear to the office. It's not just for guys. Art director Matilda Kahl has been wearing the same outfit to work for the past three years, and she looks fantastic doing it. Like eating nothing but Soylent, it's an extreme move, but one that could add even more time to your schedule.