[mr_mitm]

Same way you bend space. In GR, time is just another dimension of a slightly different flavor.

[ikekkdcjkfke]

Whats the actual mechanism though?

[mr_mitm]

You contribute to the stress-energy tensor by having mass or energy. That directly influences spacetime curvature. The Einstein field equations tell you how precisely.

If that answer doesn't satisfy you, I'm afraid that's all we can say. It reminds me of Feynman's answer on how magnets work: https://www.youtube.com/watch?v=MO0r930Sn_8