The honest answer for you for any of the modalities you mentioned is that you willspend a considerable sum of money with very limited, if any results. Skin tightening can be achieved by skin resection, but the scars may be unacceptable. Surgical treatments may range from a tummy tuck to body lift to inner arm lift. You would need to be examined to determine the success of any of these procedures.
If it just started you could help your skin from the inside and out. What is your diet like? I found some improvememt in my skin using really good supplements. Check out http://www.beyondhealth.com I am NOT affiliated in any way with this website or the owners other than my husband heard the owner and founder Dr. Raymond Francis speak at a convention a few years ago and I liked the literature he brought home. Check it out for yourself but it helped my skin and I live in the desert where my skin really needs help. I also moisturize after getting out of the bath or shower with Nutrogena sesame body oil and Nivea skin firming moisturizer w Q10 plus.it isn't a miracle but it has helped. Stretching is good, yoga and Pilates type workout is good. Keeps your facia fexible and helps support your muscles. Also, There is a laser that may help called Accent laser. It is used specifically for the areas you mention but not sure about the costs vs results. If I had an unlimited budget I would try it but since I don't I haven't. My cosmetic Dr has one and he said it doesn't work well on the face but he's seen decent results w the loose skin under your arms.you might also want to supplement with Glucosamine, chondroitin (sp?) and MSM good for joint fluid and connective tissue. Make sure u get your supplements from a good source though wherever u choose to get them. The grocery store and drug store supplements are full of preservatives and not derived from the best sources and hence are a waste of money since your body won't assimilate them. Read about Dr Francis and his story. He explains it all in detail. They are not cheap but I do see a difference, it doesn't happen overnight. It took about 8 months of really eating well and supplementing.have you been crying more than normal? Are you menapausal yet? Peri or post? If so I really like black cohash! Also green tea! Vits A, C, D, E, all your Bs Calcium, Folic acid all the micro nutrients and anti -oxidants and all the good healthy fats! Maybe you are not giving your skin the nutrients it needs which needs more as we age cause our bodies just are not as efficient at uptaking the nutes. Make sure you stay hydrated but not to the point where your urine is clear or you are flushing too many nutrients out of your body! If all else fails there is always surgery but as the good Dr said the scarring and price may not be worth it at least not yet. As for working out harder, its better to work out smarter. Trick your body with new routines you probably are just used to your routine and your body isn't challenged. Attack from the inside and out! Tell yourself how tight and young looking your skin is too. Tell it to remember what it felt like when you were 19. They are only cells after all. What do they know? Lol it's part of the "think it and it will be so" way of thinking. Better than worrying about wrinky skin which WILL give you wrinky skin! :-) Lastly, check w a dermatologist as well to see if there is anything he/she might suggest. keep up the good fight! Don't give in. Your just getting better.