I’ve been following two exceedingly good channels in YouTube: Fitness Blender and Athlean-X. Classic example that will put you out of breath in a jiffy:

Tech note: first usage of partial include in Jekyll - a nice wrapper for embedded YouTube videos that fills viewport’s width.

Jeff from Athlean-X has given some very thourough explanations about postures and his understanding of muscles is exceptional, highly recommended.

Fitness Blender’s couple have simply the best HIIT workouts out there - I can barely complete most of those 20-minutes videos. Intense and concetrated on core - hips/glutes, the most beneficial type of exercises for those who sit on a chair for the majority of their lives, like me. Another pro - most of the exercises do not involve any equipement. It may be nice to beef up later with weights, but it would probably not be wise to try to puff up without the perfect posture first.

Balance. Keep the balance. Always walk straight and do not lean when standing, especially when you have a weak side (I do).