This is my own solution, improvements welcome :)

Check for term ID and assign to variable.

    
    $term_id = (has_term('activity_1','activity-tax') ? 1 : (has_term('activity_2','activity-tax') ? 2 : (has_term('activity_3','activity-tax') ? 3 : '')));

Use term ID variable in my get_posts parameters. 

    $args = array(
	'post_type' => 'activity-post',
	'order' => 'ASC',
	'tax_query' => array(
		array(
		'taxonomy' => 'activity-tax', 
		'field' => 'term_id', 
		'terms' => $term_id) // Only the ID I want
	)
	); 
    $posts = get_posts($args);

Run over each post and create multiple array of meta data.

	$custom_post = array();
	foreach ($posts as $post) {
		$custom_post[] = get_post_custom($post->ID);
	}

Finally get the array's meta data I want.

	foreach ( $custom_post as $key => $value ) {
		echo $value['date'][0].'<br />';
		echo $value['duration'][0].'<br />';
		echo $value['paypal'][0];
	}