[header] How to prepare for a high altitude hike [title] Begin training well in advance. [step] Plan the amount of training you will do based on the difficulty of your hike, and your current fitness level. If you are reasonably fit, and attempting a challenging hike, then you will probably want to schedule at least 5 months of training before your hike is scheduled. 
If you are really out of shape, you may need to train for much, much longer. [substeps] Remember that you can never start training too early, but you can start too late.