从字面上理解， keep a clear mind 就是保持头脑清醒，思维清晰的意思，如： Taking exercise helps us build up our body and keep a clear mind. 参加体育活动有助于增强体魄并保持头脑清醒。 keep an open mind就是保持一个开放的心态，开明...

you'll always be in my mind and my heart,And...You are my future and nothing can ever keep us...setting over a serene pool of crystal clear water...