Update monitor :tada:
diff --git a/rackspace/lb/v1/monitors/requests.go b/rackspace/lb/v1/monitors/requests.go
new file mode 100644
index 0000000..dac0cab
--- /dev/null
+++ b/rackspace/lb/v1/monitors/requests.go
@@ -0,0 +1,157 @@
+package monitors
+
+import (
+	"errors"
+
+	"github.com/racker/perigee"
+
+	"github.com/rackspace/gophercloud"
+)
+
+// UpdateOptsBuilder is the interface options structs have to satisfy in order
+// to be used in the main Update operation in this package.
+type UpdateOptsBuilder interface {
+	ToMonitorUpdateMap() (map[string]interface{}, error)
+}
+
+// UpdateConnectMonitorOpts represents the options needed to update a CONNECT
+// monitor.
+type UpdateConnectMonitorOpts struct {
+	// Required - number of permissible monitor failures before removing a node
+	// from rotation. Must be a number between 1 and 10.
+	AttemptLimit int
+
+	// Required - the minimum number of seconds to wait before executing the
+	// health monitor. Must be a number between 1 and 3600.
+	Delay int
+
+	// Required - maximum number of seconds to wait for a connection to be
+	// established before timing out. Must be a number between 1 and 300.
+	Timeout int
+}
+
+var (
+	errAttemptLimit = errors.New("AttemptLimit field must be an int greater than 1 and less than 10")
+	errDelay        = errors.New("Delay field must be an int greater than 1 and less than 10")
+	errTimeout      = errors.New("Timeout field must be an int greater than 1 and less than 10")
+)
+
+func withinRange(val, min, max int) bool {
+	return val > min && val < max
+}
+
+// ToMonitorUpdateMap produces a map for updating CONNECT monitors.
+func (opts UpdateConnectMonitorOpts) ToMonitorUpdateMap() (map[string]interface{}, error) {
+	type m map[string]interface{}
+
+	if !withinRange(opts.AttemptLimit, 1, 10) {
+		return m{}, errAttemptLimit
+	}
+	if !withinRange(opts.Delay, 1, 3600) {
+		return m{}, errDelay
+	}
+	if !withinRange(opts.Timeout, 1, 300) {
+		return m{}, errTimeout
+	}
+
+	return m{"healthMonitor": m{
+		"attemptsBeforeDeactivation": opts.AttemptLimit,
+		"delay":   opts.Delay,
+		"timeout": opts.Timeout,
+		"type":    CONNECT,
+	}}, nil
+}
+
+// UpdateHTTPMonitorOpts represents the options needed to update a HTTP monitor.
+type UpdateHTTPMonitorOpts struct {
+	// Required - number of permissible monitor failures before removing a node
+	// from rotation. Must be a number between 1 and 10.
+	AttemptLimit int `mapstructure:"attemptsBeforeDeactivation"`
+
+	// Required - the minimum number of seconds to wait before executing the
+	// health monitor. Must be a number between 1 and 3600.
+	Delay int
+
+	// Required - maximum number of seconds to wait for a connection to be
+	// established before timing out. Must be a number between 1 and 300.
+	Timeout int
+
+	// Required - a regular expression that will be used to evaluate the contents
+	// of the body of the response.
+	BodyRegex string
+
+	// Required - the HTTP path that will be used in the sample request.
+	Path string
+
+	// Required - a regular expression that will be used to evaluate the HTTP
+	// status code returned in the response.
+	StatusRegex string
+
+	// Optional - the name of a host for which the health monitors will check.
+	HostHeader string
+
+	// Required - either HTTP or HTTPS
+	Type Type
+}
+
+// ToMonitorUpdateMap produces a map for updating HTTP(S) monitors.
+func (opts UpdateHTTPMonitorOpts) ToMonitorUpdateMap() (map[string]interface{}, error) {
+	type m map[string]interface{}
+
+	if !withinRange(opts.AttemptLimit, 1, 10) {
+		return m{}, errAttemptLimit
+	}
+	if !withinRange(opts.Delay, 1, 3600) {
+		return m{}, errDelay
+	}
+	if !withinRange(opts.Timeout, 1, 300) {
+		return m{}, errTimeout
+	}
+	if opts.Type != HTTP && opts.Type != HTTPS {
+		return m{}, errors.New("Type must either by HTTP or HTTPS")
+	}
+	if opts.BodyRegex == "" {
+		return m{}, errors.New("BodyRegex is a required field")
+	}
+	if opts.Path == "" {
+		return m{}, errors.New("Path is a required field")
+	}
+	if opts.StatusRegex == "" {
+		return m{}, errors.New("StatusRegex is a required field")
+	}
+
+	json := m{
+		"attemptsBeforeDeactivation": opts.AttemptLimit,
+		"delay":       opts.Delay,
+		"timeout":     opts.Timeout,
+		"type":        opts.Type,
+		"bodyRegex":   opts.BodyRegex,
+		"path":        opts.Path,
+		"statusRegex": opts.StatusRegex,
+	}
+
+	if opts.HostHeader != "" {
+		json["hostHeader"] = opts.HostHeader
+	}
+
+	return m{"healthMonitor": json}, nil
+}
+
+// Update is the operation responsible for updating a health monitor.
+func Update(c *gophercloud.ServiceClient, id int, opts UpdateOptsBuilder) UpdateResult {
+	var res UpdateResult
+
+	reqBody, err := opts.ToMonitorUpdateMap()
+	if err != nil {
+		res.Err = err
+		return res
+	}
+
+	_, res.Err = perigee.Request("PUT", rootURL(c, id), perigee.Options{
+		MoreHeaders: c.AuthenticatedHeaders(),
+		ReqBody:     &reqBody,
+		OkCodes:     []int{200},
+	})
+
+	return res
+}