The Standard Model is our best current theory of fundamental interactions. Despite its success there is a number of examples hinting at new physics beyond it, such as dark matter and the baryon asymmetry of the Universe. One way to probe the existence of new particles is through indirect precision tests, where high-precision theoretical predictions are scrutinised in the light of experimental measurements. A recent example of such a test at low energies is the muon anomalous magnetic moment, where a long-standing tension recently was resolved in favour of the Standard Model. Beyond the muon g-2 there is a number of tensions requiring both theoretical and experimental improvements. In this talk I will give a brief overview of some flavour-physics hadron decays in the light-quark sector, where the sought level of precision requires both good control of non-perturbative effects and the inclusion of isospin breaking. I will discuss some non-perturbative tools at hand (lattice and effective field theory), how they are complementary and are currently being used together for explorations of physics beyond the Standard Model.
