Movies like THE FANTASTIC FOUR (2005 version) and SPIDERMAN seem to get the emotional cost of power right. For example, Peter Parker and Ben Grimm face emotional difficulties by having that second identity and the need to save the world, one villain at a time.
Peter has a rough time with relationships and finances because he's always running off to wear that red spider suit, and he has a weird, but not likely tendency, to have friends and professors who have a supervillian within or as a member of the family.
Poor Ben Grimm gets changed into The Thing who makes the Incredible Hulk look like the Incredible Hunk, and at two tons with massive hands, he finds the simplest task like eating or lifting a coffee cup just about impossible. He also loses his wife who can't deal with his physical change, and he's stared at and shunned.
What these movies and the comics they are based on sometimes don't get right is the physical cost of having a superpower.
Johnny Storm, The Human Torch, of THE FANTASTIC FOUR, is a perfect example. He puts out an incredible amount of heat when he ignites himself and flies. At the end of the movie, he is involved in a long chase scene then becomes a supernova, but he is only winded by the end of the final confrontation with Dr. Doom.
Where does this energy come from, and why isn't he starving or weak after such an expenditure?
The reality is that he should be since these comics are based on pseudo-science, and energy isn't infinite even in pseudo-science.
By giving a superhero limitations in power, the writer is also making the story more exciting because a certain weakness means possible defeat.
Just think of Superman and Kryptonite. Superman isn't very exciting when he's fighting criminals because we know all the bullets will bounce off the chest but toss in Kryptonite, and he's as mortal as the rest of us.
In your own writing, remember to include the physical cost as well as the emotional cost for your characters, superheroes or not, and your story will be much more exciting.
Now, "Flame On!" but remember to have your character completely depleted and moving on courage by the end of the final fight and have him stop by the all-you-can-eat buffet to celebrate his victory.