I know this sounds crazy
but I swear it works: As long as there is no metal on the shoes (tips of shoelaces, ringlets around lace holes,
etc.)
, put the shoes in the microwave for 15-20 seconds.
Then take them out and immediately put them on your feet with thick socks on and tie them as tightly as possible.
Walk around until the shoes completely cool down.
This should really work them in and you can always repeat the process if you would like.
Depending on the type of shoe, you may want to microwave it for longer
but I would suggest trying a short length of time first than slowly add more time until it is a good comfort level for you.
This works because the shoes heat up and, by tying them very tightly while they are still warm, they form to the shape of your foot, making them more comfortable.
Source: years of skateboarding and constantly trying to wear in shoes as quickly as possible.
lifehacks.stackexchange.com/users/1335/celeriko
I speculate that wearing thicker socks will help with both the accelerated "wearing in" by stretching the shoes more and with the reduced discomfort by providing a physical barrier between your skin and the currently ill fitting shoes.
If the shoes are uncomfortable because they are simply too tight (as opposed to "hard" and abrasive around the foot hole), then thicker socks are unlikely to work.
You could get somebody else to wear them for you ;)
lifehacks.stackexchange.com/users/47/James Webster
A few methods to consider: Get them wet and wear them for a few hours.
Sounds counter intuitiveI know, but most leather shoes/boots are pre-shrunk so wetting andwearing will help to stretch them out and form them to your feet.
I've used this method with combat boots and it seems to work well.
Spraying the inside of leather shoes/boots with equal parts 1:1
waterand alcohol will soften and help to stretch the leather.
This issimilar to the process used by leather workers to form the leather tobegin with so it may be worth a try.
I'm not too sure about this one...
I haven't tried it personally, buta few sites recommend filling a zip-lock bag half way with water andplacing it inside the shoe/boot and putting it in the freezer.
Theidea is that the water will expand as it freezes and will stretch theleather.
lifehacks.stackexchange.com/users/32/apaul
The best hack for this is to use heat because heat makes things expand.
All you will need is a hairdryer, a thick pair of socks (or two thinner pairs of socks), and your shoes.
Put the socks on and then put the shoes on.
Now, put the hairdryer on the highest heat.
Blow dry the areas where the shoe needs to form to fit your foot (usually the toe and maybe the sides).
Bend and flex your feet while you are blow drying.
You usually have to do this for 20-30 minutes per shoe.
Make sure to hold the hairdryer at least 2 inches (5 cm) away from the shoe to avoid damage.
This question is being closed as a dupe, and this was my answer on it (slightly modified)
lifehacks.stackexchange.com/users/20/michaelpri
I had some uniform shoes which weren't wide enough, and the shoe-shop lady sold me some wooden shoe stretchers - essentially feet with springs in - and advised me to put wet socks on them and leave them overnight.
This helped, but since they still weren't quite wide enough I wrapped paper around the stretchers, a bit more each day, and repeated the process.
lifehacks.stackexchange.com/users/2569/RedSonja
There are these things:
I have no clue how they are called in english, but they are called "Schuhspreizer" in German (could translate into "shoe widener").
You put them into your shoes and they will widen them.
lifehacks.stackexchange.com/users/5176/AlexWerz
I was told about this hack.
I have heard about it more than once from different sources; but, I have never tried it myself.
To stretch (break-in) new leather shoes so that they are comfortable to wear, carefully line each shoe with plastic such as a thick sheet of plastic or use a heavy gauge plastic freezer bag.
Push the plastic into each shoe as far and as completely as you can.
Lace up and tie the shoelaces securely.
Fill each plastic lined shoe with water up to the brim and freeze it SOLID in a freezer.
The ice inside the bag in the shoe will take the shape of the shoe.
The water will freeze, swell, and stretch the leather proportionately as it increases size.
When the water has frozen solid, the process is finished and the bag and ice can be removed.
The shoes should fit perfectly.
If more stretching is wanted, repeat the process.
lifehacks.stackexchange.com/users/4698/Stan
I have a new pair of leather shoes, and "wearing them in" promises to be uncomfortable for a little while. In the past, I've tried to solve this problem by wearing my shoes, which isn't preferable because it's uncomfortable.

How can I wear my shoes in faster, or reduce the discomfort, while still getting the benefit of having shoes that have worn to fit the shape of my feet?
How can I "wear in" my shoes without wearing them?
lifehacks.stackexchange.com
<comfort><shoes>
lifehacks.stackexchange.com/questions/2136
lifehacks.stackexchange.com/users/1472/Yann
There are a number of different ways of "wearing in" shoes without wearing them. You could try applying heat, either by putting them in the microwave for 15-20 seconds or by blowing them with a hairdryer. Alternatively, you could fill two freezer bags with water, put them in the shoes and the put the shoes in the freezer. Some shoe shops may sell some form of shoe-stretching tool. The options include microwaving the shoes for 15-20 seconds, wearing thicker socks for a while to loosen them up, wearing them wet for a few hours, heating them with a hairdryer whilst flexing, using shoe stretchers or freezing bags of water in them.
Microwave the shoes for 15-20 seconds then put them on immediately when still hot and walk around in them. Repeat process until they feel comfortable. Try wearing thicker socks for a while as long as they are not too tight - or get someone else to wear them in for you. Get them wet and then wear them for a few hours. Put the shoes on wearing thick socks and then heat them with a hair dryer for 20-30 minutes in the relevant areas, flexing your feet in the meantime. Put wooden shoe stretchers with wet socks on into them overnight. Pad the stretchers with paper as required. Put a plastic bag into each shoe, tie the laces, fill the bags with water and place in freezer until solid.