I like the hero point option from the APG but my guys are always spending them early so for several sessions, they don't even have the option.
I came up with a similar system that gives some of the same options as the hero point but does so by the characters pushing their bodies and minds to the point of exhaustion. This limits its overuse but makes it more usable in some ways and gives some level of consequence.
EXTRA EFFORT SYSTEM
Extra Effort can be used by a player character at any time as a free action. It is something only heroes are truly capable of so it is not usable by NPCs or opponents.
Extra Effort can be used for a physical or mental boost.
Physical includes altering the roll or effect of anything other than a spell, spell-like ability or supernatural ability, making a fortitude or reflex saving throw, a skill roll that uses a physical attribute or other actions that are easily determined as physical. Using extra effort for a physical action will leave the character fatigued at the end of their turn. If used while the character is already fatigued (such as from using extra effort already) the character is left exhausted. Note that fatigue lasts until the character has a chance to rest for 8 hours and exhaustion lasts until the character can rest for one hour.
A mental boost includes altering the roll or effect of a spell, spell-like ability or supernatural ability, a will saving throw or any skill or ability check that uses a mental ability and other actions that are determined by the GM to be "mental" in description. Using extra effort for a mental action leaves the character sickened until the character has had a chance to rest for 8 hours. If the character is already sickened from using extra effort, the character is instead nauseated until they can rest for 1 hour.
Extra Effort can be used to do any of the following. GM and the text above determines if this constitutes a physical or mental exertion.
Act Out of Turn: You can take your turn immediately. Treat this as a readied action, moving your initiative to just before the currently acting creature. You may only take a move or a standard action on this turn.
Bonus: If used before a roll is made, extra effort grants you a +8 luck bonus to any one d20 roll. If used after a roll is made, this bonus is reduced to +4. You can use extra effort to grant this bonus to another character, as long as you are in the same location and your character can reasonably affect the outcome of the roll (such as distracting a monster, shouting words of encouragement, or otherwise aiding another with the check). Extra effort spent to aid another character grant only half the listed bonus (+4 before the roll, +2 after the roll).
Extra Action: You can use extra effort on your turn to gain an additional standard or move action this turn.
Heroic Feat: You can acquire a feat for the duration of the round you are using extra effort. You can bypass some prerequisites for the feat except for level, race or background requirements. GM has final determination as to what is allowable.
Metamagic: You can apply a metamagic feat you know spontaneously without increasing the casting time (for spontaneous casters) and at a reduced level modification. This is obviously a mental application of extra effort. A reduction of -1 (to reduce the modifier for Enlarge spell to zero for example) will leave the character sickened and a reduction of -2 (to make empower spell's modifier +0 for example) will leave the character nauseated.
Recall: You can use extra effort to recall a spell you have already cast or to gain another use of a special ability that is otherwise limited. This should only be used on spells and abilities possessed by your character that recharge on a daily basis.
Reroll: You may use extra effort to reroll any one d20 roll you just made. You must take the results of the second roll, even if it is worse.
Special: You can petition the GM to allow extra effort to be used to attempt nearly anything that would normally be almost impossible. Such uses are not guaranteed and should be considered carefully by the GM. Possibilities include casting a single spell that is one level higher than you could normally cast (or a 1st-level spell if you are not a spellcaster), making an attack that blinds a foe or bypasses its damage reduction entirely, or attempting to use Diplomacy to convince a raging dragon to give up its attack. Regardless of the desired action, the attempt should be accompanied by a difficult check or penalty on the attack roll.
Cheat Death: A character can use extra effort to cheat death. How this plays out is up to the GM, but generally the character is left alive, with negative hit points but stable. For example, a character is about to be slain by a critical hit from an arrow. If the character spends 2 hero points, the GM decides that the arrow pierced the character's holy symbol, reducing the damage enough to prevent him from being killed, and that he made his stabilization roll at the end of his turn. Cheating death is the only way for a character to spend more than 1 hero point in a turn. The character can spend extra effort in this way to prevent the death of a familiar, animal companion, eidolon, or special mount, but not another character or NPC. Using extra effort in this way always leaves the character either exhausted or nauseated as if it had been used twice.
Any suggestions or ideas?