I think it is 'could' instead of 'cloud' in the last sentence. In my point of view, It basically means that we must stop comparing our properties(personality, skills, capabilities, etc) with others. The last sentence says that the time we spend comparing we could use to improve our own properties not based in someone's else properties but ours. Therefore, the more you look to yourself and the things that you should improve the more you help to build your inner resources.

When we make ourselves miserable by comparing ourselves with others ,we are wasting time,energy that we could use in building our own inner resources. It means that when you make yourself unhappy by comparing yourself to someone else, you could use that time and energy to make yourself a better person or to make yourself happier.