The phrase "to add some challenge" means making a task or activity more difficult or demanding, to make it more interesting or engaging. Full definition
Based on a traditional model that fuels competitiveness, the industry faces added challenges of an unpredictable market and too few barriers for entry. (rismedia.com)
When faced with added challenges on top of normal teen issues, your child might be at higher risk for severe depression, which can lead to suicidal thoughts and actions. (tacomachristiancounseling.com)
Add some challenge by asking your child to draw another picture of something that begins with the same sound as the picture you drew. (readingbrightstart.org)