If you have a MyFit liner, you can heat mold them in a pre-heated oven at 180 degrees F for 7 minutes, remove them, fit them quickly inside the skates, put your foot in and lace them up really tight, as tight as you can. You can now sit and wait 10minutes for them to cool down. Next time you go skate, your pain will be gone.

Second tip: if they are not heat moldable, just skate them and break them in. 1-2 months of skating at least 2 days a week should do it