Finding special Lagrangian submanifolds in Calabi-Yau manifolds has been an important problem in complex geometry and symplectic geometry. In this talk, I will introduce a new gluing construction of special Lagrangian submanfiolds in K3-fibered Calabi-Yau 3-folds, whose Calabi-Yau metrics are sufficiently collapsing. In particular, this gluing construction produces special Lagrangians homeomorphic to S^3 and S^1 x S^2 corresponding to "segments" and "loops", respectively. This result verifies an expectation of Donaldson and provides a preliminary step toward understanding the relationship between gradient cycles and special Lagrangians, as conjectured by Donaldson and Scaduto. This is joint work with Yu-Shen Lin.