This laying on of ashes was done on Wednesday, the day named for Odin, Odin’s Day. And the German word for the day called Wednesday in English is “Mittwoch” or mid-week, in French it is mercredi; in Spanish, miércoles; and in Hebrew it is pronounced Yom-re-vee-EE.
Nothing related to Odin in those, thus we have merely false linking of doing ashes to worshiping a pagan god based upon the linquistic orgin of a word for a day of the week — pretty weak logic in my view.
If your satisfied with the “full reward” (Matthew 6:16-18) of being seen publicly displaying some sort of pious ritual have at it. Many of us would much rather be rewarded by God for doing it in secret. Don’t be shocked however that we will show what God has to say on the subject rather than some religious organization.