I’m 19 but still have a boyish body. Im skinny but have a small belly and almost no pectorals. I don’t think I’ll sign up for a gym this summer as I’m landscaping anyway and I do quite a bit of lifting for that. However landscaping mostly is arms and back. I’d love to have a barbell at home to beach press with.
It depends if you want to look toned or big or both the latter you would definitely need to go to the gym but what is your height and weight that's a huge factor too ?
I'm an ectomorph so always look lean and 'skinny' unless I put serious weight through weight training and food. I think I have properties from the other body categories as i have wider hips than usual but still retain narrow clavicles and smaller joints like wrists and ankles.
In order to help speed up the process of putting on muscle be sure to do works out that use large muscle groups especially squatting because when doing leg excercise your body releases the most testosterone
Start with compound exercises to lay a good foundation for some strength, then proceed to isolation movements and despite what anyone says, do your cardio, just not excess of it