Each fire tower quest give you achievement

0:00 Worlds best dad
5:51 Most perceptive person
9:22 Most carefull person
12:01 Coolest hand
17:23 Most responsible person
22:41 Mister Falconer

The gym is located in chapter 4 (the part with the bathroom in a pit, box hell, and a diving board. You want to reach the diving board, jump in the water and swim toward the hole inside the water before you surface up.

Here is the gym in question

Here is a video of me doing both in the same run. The video is long so the big advice is mostly knowing where to go, and don't forget to bring the clock/steps counter with you, depending on which you do

For the podometer, leaving it inside the sand castle and coming back after finishing it is the best way to do it, that way, you save steps on the house section and the climb to the angel.

You can also swim like in the beginning of desert, just go straight in the water and swim to the campfire instead of walking all the way there

Jiminy's Cricket : climb the staircase before the ice section instead of taking the manbreaker

Cassie's Trophy : At the start of the desert, there is a turtle going round and round near the long lake, catch the trophy on its head (reference to the hare and the turtle?) and bring it to the desert campfire, and complete the mini game.

And including it in this category too, Ready for a Different Game since you've done everything

This is the hidden achievement so skip this if you don't want to see it. This is the way to cheese it but feel free to do it normally if you'd like