Men will deliberately give you the impression that they're fine on their own, they know what they're doing, and they cope with anything. They like to play the hero. In reality, they're no different to you - they need emotional support and understanding, and reassurance that they're on the right track.
This can come in many forms; if there's a promotion open at work and they're not sure they're right for it - but you just know they are - tell them. Encourage them to push themselves and drive forward. Equally, they may have a hobby or interest that's nothing to do with work or you - perhaps they play amateur sports, or perform music or paint, and you have no interest in it and it doesn't have any benefit to you. It's still important to them, and it's something they enjoy, so take an interest in it and encourage and support them. If they feel they have your blessing, you become part of their success and they'll love you for it.