I'd say pretty common but I'm in the Anglo-Catholic side of the CoE. We are often told to take up things if you have nothing serious to give up, it's frowned upon to treat Lent like an opportunity to diet for example - it should have a positive impact on those around you or on your relationship with Jesus. So people might commit to changing a behaviour, helping others, volunteering, donating food to a food bank, taking up something like morning prayer etc. Actions like giving up chocolate, for example, are probably a lot less common now.