Push, pull, squat, hinge. The four movements that build everything else.
Every functional movement your body makes traces back to four patterns: push (moving load away from your body), pull (moving load toward your body), squat (loading your legs while keeping your torso upright), and hinge (loading your posterior chain by bending at the hips). Master these four in bodyweight form and you have the foundation for every athletic demand life will put in front of you — including more advanced strength training, surfing, skating, and everything else.
Bodyweight training requires nothing but your body and floor space. Push-ups build chest, shoulders, and triceps — and when done with correct form, significant core stability. Pull-ups are the single best upper body pulling exercise that exists. Bodyweight squats and lunges build the leg strength that makes every sport easier. Planks and hollow-body holds train the trunk stability that protects your spine and transfers power.
The progression path in bodyweight training is genuinely sophisticated. A beginner works toward a solid push-up. An intermediate athlete works toward archer push-ups and ring dips. An advanced athlete works toward the planche and one-arm push-up. You will never 'run out' of challenge — and the strength you build translates directly to everything else you do, because you're always moving your own body through space.