[header] How to develop a manly voice [title] Stand up straight. [step] When you slouch, your limiting how much you can expand your lungs. If you can breathe in more air, your voice will be stronger, and it's less likely that your voice will crack. 
[title] Breathe from your diaphragm. [step] If you're like many people, you breathe from your chest without much support from your diaphragm.