I think that both「ついてこそ」and「ついたからこそ」can be fit into the above sentence. However, the textbook gives「ついてこそ」as the right answer and I don't know why.
Using ～た sounds like it's confined to one specific instance and not a general statement. If the rest of the sentence was also ～た it would be ok IMO, but again different from what the general statement is saying.
Think also about what ～て implies with respect to aspect: completeness of the action.
It is precisely by having got into the most routine of routines -- get up in the morning -- that one can move on to other activities.