\documentclass{article} \usepackage{tcolorbox} \usepackage{xsim} \usepackage{needspace} \DeclareExerciseEnvironmentTemplate{custom} {% \Needspace*{5\baselineskip} \begin{tcolorbox} \textbf{\XSIMmixedcase{\GetExerciseName}~\GetExerciseProperty{counter}.}% \GetExercisePropertyT{subtitle}{ \textit{#1}}% \end{tcolorbox} \noindent } {\vspace{\baselineskip}} \xsimsetup{exercise/template = custom} \usepackage{lipsum} \begin{document} \begin{exercise}[subtitle=Foo bar baz] \lipsum[1] \end{exercise} \lipsum[2] \end{document}